Karen Gillan on her debut film, Not Another Happy Ending.

1) In which we set our scene

Perky is the best word for her. It's the obvious one, too, but sometimes you can't ignore the obvious. Maybe at a push you could use sassy, but that's more American and in-your-face than is strictly accurate so, no, let’s stick with perky.

Karen Gillan breezes – perkily – into a Glasgow hotel to put on some clothes and have her picture taken. She is nearly at the end of an intense three-week film shoot but the 25-year-old is still unflaggingly bright  – sickeningly so, if like me you're feeling your years – bush-baby-eyed and glossy-maned (there are fan websites devoted to her hair).

She is in town shooting Not Another Happy Ending,  a Glasgow romantic comedy that attempts to suggest the city is not all Buckfast and razorblade smiles. The suggestion is that it's a little bit Woody Allen after a few Tunnock's teacakes, if we're lucky.

It's the film that’s been chosen to close this year's Edinburgh International Film Festival. Behind her this morning, already time-travelling into the past, are her years as Doctor Who's assistant Amy Pond. Ahead of her, as yet unrevealed, is a leading role in the Marvel sci-fi film Guardians Of The Galaxy (she's playing the bad girl in that; the point where perky becomes pesky?). But for the moment she's happy to be making something that is based on real-life, normal people.

Or normalish. In Not Another Happy Ending she’s playing a successful novelist who has lost her mojo. If this is her Woody Allen movie does that make her Diane Keaton? "I wish! I love her soooo much." (I'm actually being conservative with the number of Os in that "so". She really stretches it out for emphasis.) "Actually, the outfits in this are inspired by her look and I'm a really big fan of hers, so to be in the same sentence as her would be an honour."

2) The bit where Karen Gillan (and her director) talks about her new film and how it relates to her own situation

The reason Gillan was cast in Not Another Happy Ending, her director John McKay says, is star power. "She’s incredibly watchable, and people just warm to her – she can do fiery, she can do sexy, she can do sweet: she has all the hallmarks of a classic screwball actress, like Katharine Hepburn or Diane Keaton." Natch.

"But the great thing about Karen is she's consistently surprising," he adds. "You think: 'Bambi on Irn-Bru' – ditzy, harmless – but when she had to throw a pot plant at Stanley Weber, her leading man, she hit him square on the kisser, from 30 feet, first time, every time. And laughed. Never underestimate the  ginger biscuit …"

The thing you need to know about the novelist Gillan plays in Not Another Happy Ending is that she's going through "second album syndrome", the actor explains. "She's had a successful first novel and suddenly her life is back on track and she's feeling good about herself and therefore she doesn't have any material to write about."

In short, she's too happy and successful. Is this a problem Gillan has encountered herself, now that she's successful and gives every appearance of being happier than Simon Cowell the day after he's received his latest cheque from ITV? "Well, I sort of don't feel I've achieved all of the things in my life that I want to achieve. So I don't feel I can sit back and I've done what I wanted. I'm still on that journey. I'm somewhere  in the middle."

3) In which, on account of her latest role, we ask the first of a series of questions derived from  book titles

When did you last see your father?  (Blake Morrison, 1993)

"When he came down to the set the other day and sat around for a while and was excited for 15 minutes and then got bored."

Was he distracting you? "No, he just sits back quietly and watches. But then my mum came down to set and she’s actually in the film as an extra. I sprung it on her. She got forced into it."

4) On childhood in Inverness, discovering acting and “wild” teenage nights

What, I ask Karen Gillan, was the best day of your childhood? "Probably going to the local shows. In a field. In Inverness. I went there as a kid and I was like, 'This is no  big deal because tomorrow I'm going to Disneyland Paris.' So that feeling of the potential of Disneyland Paris combined with me being at the local fair was the best."

Gillan was born in 1987 (dear reader, what age were you in 1987? Let's just say I was long past getting excited by the prospect of Disneyland Paris), the only child of Marie and John. She grew up learning the piano and wanting to be a singer, "because my dad sings a lot". A jazz singer, to be precise, "like Ella Fitzgerald, because that’s who I loved". Don't set your ambitions so low, Karen.

"Yeah," she laughs. "I'm just like Ella Fitzgerald … I sound nothing like her. And then I was introduced to acting and it took my interest and I went to study it at 16  and that was it."

Childhood seems to have passed by happily, perkily. No huge traumas. The worst day she can think of was the day leading up to her piano exams. "I remember really dreading piano exams."

What was it about them that bothered her? A fear of failure? Of embarrassment? “I think it's fear of humiliation or something. And that’s something I’ve taken with me in life and tried to combat. Because as an actor you’ve got to get rid of that fear because at some point you are probably going to get humiliated if you take any sort of risk.

"And that's the sort of person I want to be. Someone who takes risks."

Describe a typical teenage day or night. "Actually, up until I was 16 I was doing an intense amount of acting classes, so in the day I'd be at school and at night I’d do classes … which is really boring."

That's a rubbish answer, I tell her. She laughs. "It’s true though."

OK, tell me about your first wild teenage night. "Probably going to the cinema and talking to some boys for the first time. That was exciting. 'Oh god, talking to members of the opposite sex. I don’t believe it.'"

You didn’t do that at school? "No. Or they didn't want to talk to me. I don’t know."

So what age were you when you talked to boys at the cinema? Twenty-five? "Yeah. It was last year. No, I was 15."

At 16 she left home and went to Edinburgh to attend Telford College and at 17 she packed all her belongings in two suitcases and headed off to Elephant and Castle in London to attend the Italia Conti stage school. She was there a year when the chance of a role on Rebus came up. She dropped out and went for it. Got the job and then didn’t get anything for a while. Ended up pulling pints. Was she good at it?

"I could draw a clover in pints of Guinness. Some people gave it back in disgust." They were probably disappointed it wasn’t a shamrock, Karen.

"It was a really great time in my life, actually. It was the most amazing experience for people-watching and learning about life. Scraping around for money and stuff, just living a normal life."

And yet acting isn’t normal, is it? It’s  a form of exposure. Or maybe disguise. Which is it for you?

"For me, I feel safer  if I'm acting than I do in having a real-life conversation with someone. Because you’ve got licence to do anything and no-one can judge you. So I feel less exposed. Acting feels like a weird, safe environment."

5) More questions derived from  book titles

When will there be good news?  (Kate Atkinson, 2008)

"When we figure out what the universe  is. Where it came from. We'll have this new-found meaning to our lives. Or maybe it will take away all meaning and it will be terrible."

Are you religious? "Not at all. My family are Catholics but I haven't been christened and I don’t practise any religion."

So we’re just miniscule dots in the vast cosmic emptiness of the universe? "Yes."

What do we talk about when we talk about love? (Raymond Carver, 1981)

"A person that we love and the feelings they conjure up in oneself."

When were you first in love? "Probably when I was about 18. It was definitely,  yeah …" What did it feel like? “Electricity."

6) The inevitable conversation  about Doctor Who

Gillan was 21 when she was chosen to be the new Doctor Who companion. Amy Pond made redheads cool and the "new sexy" and all those other things newspapers say about things that no-one really thinks about in the real world. (Of course, redheads must be sexy. Scotland would have a much smaller population if they weren’t.)

At the time she was only tangentially aware of all of this. She was too busy filming most of the time. "We shot it for nine months a year. Basically since I was  21 I've been working on that. It’s the best way to spend the last three years. I feel like I’ve learned so much. I feel like that’s the three years of drama school I dropped out of. And now, on this film, all of that is coming into play."

Any regrets about leaving Amy Pond behind? "No-o-o. Regrets are silly anyway. Just go with gut instinct."

Is it strange, though, filming and not having Daleks on set? "Yeah, it really is.  I keep on expecting one to be round the corner. I do actually really miss them. There’s nothing more fun than running away from a monster … that you can’t actually see at the time."

7) The discombobulating effects of fame  (or otherwise)

Whether she was aware of it at the time  or not (and let’s be honest, she must  have been), Doctor Who made Karen  Gillan famous. She was no longer  the girl behind the bar pulling pints  and putting clover leaves (not  shamrocks) on top.

"Yeah," she accepts, "you can’t help but be aware that people are noticing you more and therefore it does affect your behaviour, even if you try not to let it … because you don’t really want to be staggering around or drunk. There’s a certain barrier that goes up naturally if you’re in certain situations that you can’t help."

Does that mean you can’t be normal any more? "It's a small price to pay because  I still have all my friends in Inverness who  I can totally be myself around and there’s no barriers there. So I get that side of life  as well as working in a job I really enjoy.  So I can’t moan about it."

8) The best question  I will ask Karen  Gillan today (suggested by my daughter Elizabeth Jamieson, 11)

Who would you most like to be with  in a zombie apocalypse? "Dead or alive?  I’d be human, but can I have a zombie  Keith Moon? That would be really great.  I just really like Keith Moon and I'd  love to see a zombie version playing  the drums."

I’m not sure a zombie Keith Moon would have the co-ordination to play the drums. "He could go into jazz drumming."

9) The final questions derived from book titles

Who do you think you are? (Alice Munro, 1978)

"Oh my God, I don’t know … I think that’s something we’re always trying to find out in life. Do we ever know how to answer that?"

Well, then sum yourself up in five words. "Optimistic. Spontaneous. Laughy. Driven. And morbid.”
Morbid? Are you a closet goth? “There’s a small section of my brain that is … wearing dark eyeliner."

Is that it? (Bob Geldof, 1988)

"Absolutely not. That is definitely not  it. There’s so much more to come. We shouldn’t ever think that’s it, because if  we do we’re screwed."

What do you most want to experience, then? "This is genuine. I really want to go into space. And I think I might." How so?  On Virgin Galactic? "I’m going to try to get on that. Honestly, I just think it would be the most amazing experience."

10) A conclusion

Things I have learned about Karen Gillan after spending time with her in a hotel room in Glasgow.

Her mum makes her laugh more than anyone else. She is still interested in horoscopes even though she believes we are miniscule dots in the vast cosmic emptiness of the universe (see Chapter 5). "When it comes to characteristics they're really bang on." What are you? "Cancer. Sensitive … Or you go into moods."

Ten years from now she is hoping she will be a writer. She is working on a screenplay. It's quite dark. "That's where my morbid side comes in." The films she likes are dark. Like Michael Haneke's The Piano Teacher and Steve McQueen’s film about sex addiction, Shame. But don’t expect her  to appear in anything similar. “I just love watching them."

Oh and one more thing. She wants to hold on to the blind optimism of youth. “I’m trying to retain it.” I reckon she’s doing  a good job.  

Not Another Happy Ending (cert tbc) will have  its world premiere on June 30 at Edinburgh International Film Festival. More  information at notanotherhappyending.com and edfilmfest.org.uk.