Right now, Jodie Whittaker is considering what might possibly constitute adulthood. It's the quietest she's been in our time together. Admittedly I only met her ten minutes ago but I think I already know that this silence is unlike her. Since she sat down she has been talking a mile a minute in an accent that couldn't be more Yorkshire if it was wearing a flat cap and drinking tea at Bettys.

She's already told me about her new film Adult Life Skills, about the last time she urinated in the outdoors (to be fair I did ask her; her character Anna does it in the film you see), about the things you should stop doing when you reach your thirties ("Maybe renting. I'm still renting and I'm 34."), about her star sign (she's a Gemini), and about whether it does or does not always have to be about sex ("I don't think it is."). All of these are questions inspired by the movie in case you're wondering.

Adulthood though. That takes some thinking about. What does it amount to, Jodie? She has an answer for me. "Preferring to stay in than go out. Being really excited when you get eight hours of sleep whereas when you're younger you think 'it's amazing, the sun came up and I was still out.'"

Maybe that's the mother of a young child talking. Whittaker, who is married to fellow actor Christian Contreras is a mum in real life and one of the most famous mums on telly in the last few years, playing the grieving mother Beth in Broadchurch. She's filming the third series right now.

But I'm interrupting. Sorry Jodie. Adulthood. Carry on. "Guilt," she adds. "No, not guilt. But there's more shit to worry about when you're older. Not guilt. Anxiety. That's the word."

Adult Life Skills, which is getting an airing at the Edinburgh International Film Festival, hence her presence in the city this Saturday afternoon, is anxiety played for laughs. It's a sparky, small movie about, yes, grief (Whittaker plays a sister who is struggling to cope with the death of her twin brother), family and friendship, made as it happens by a group of friends. What with Broadchurch she does a lot of grief on screen. "I finished shooting season two and four, five days later I was on set for this. It's a world away from Broadchurch, but it's good practice."

In truth at the heart of Adult Life Skills is a vision of female friendships, both on and off-screen.

Whittaker's known her co-star Rachael Deering since she was three and the director Rachel Tunnard (or "Tunnard" as Whittaker keeps calling her) for years too. Nine years ago the three of them went on a trip to France during which "Tunnard", then a film editor, told her two actress friends that she was going to write a film with parts for the both of them. Adult Life Skills is the eventual result.

To get it made Whittaker became executive producer. Which mainly meant taking an extra interest on set. "On a feature you rock up and you do the job whereas on this I was very aware. I knew the budget."

And so, she says, she knew when they had to finish a scene because they were going to lose the location. She quite liked all of this extra knowledge. Why? "Just because I'm just a nosy cow. I am. I cannot help but chip in. I'm just a pain in the ass. I was destined to be an actor."

The Herald:

Adult Life Skills is also a sort of homecoming for Whittaker. It was filmed close to where she grew up in West Yorkshire. Born in 1982, as a child she lived in the village of Skelmanthorpe in 1982, watching ET and The Goonies and knowing she wanted to be an actor.

"There's a video of me and Rachael Deering when we interviewed each other when we were about 13, sat in my mum and dad's garden. Me with my mad braces. I was interviewing her. 'What is your dream when you grow up?' It was to meet Leonardo DiCaprio. Then she asked me and I was like 'to be in a Film Four film.'

"I'm not academic so I was never in that difficult position where I could be a lawyer or a doctor. I was never going to do that."

Acting, though, she could imagine doing. She remembers thinking "well, I love it and I seem to be all right at it so if I can I'll go to drama school." Plus, she admits she has a "massive ego".

Well-founded as it happens. She first made a splash opposite Peter O'Toole in the film Venus, written by Hanif Kureishi (a Film Four movie as it happens; so that box was ticked off at the first time of asking).

Before that she had funded her time at drama school by working in a bar. Could she pour a Guinness? "Yeah. I can do a shamrock because I worked at O'Neills."

After Venus she didn't have to. Parts on TV and in the St Trinian's movies followed and she was soon a regular in TV dramas as well as the odd big screen outing. She shone in the Belfast movie Good Vibrations, though few have seen it and in London sci-fi monster movie Attack the Block.

But it's Broadchurch that really got her noticed. Although only, she says, when her hair is brown. When she's wearing what she calls her "Beth hair". In real life, she says, she's a peroxide blonde.

Did she know that she had landed a part in something special when she got the part of Beth? "When we were shooting it I can remember having a conversation with a friend saying 'if I'm terrible in this I've really let myself down because I've been given all the opportunities. All the other actors were amazing, the crew was amazing and the writing is fantastic.'"

Adult Life Skills is a more intimate, less intense pleasure but a pleasure nonetheless. It's also a film that makes no apologies for telling a woman's story. Is that something we get enough of Jodie?

"No. You know the answer to that. What is frustrating … I say this all the time. I'm quoting myself because I was really proud of my own quote … We're not a genre yet it gets written as a genre. 'Female cinema'. It's not a genre. We're 50 per cent of the population.

"And the amount of male people in my life who have seen it and loved it … I'm not put off by a male story."

Just as well really. "Yeah. I wouldn't be at the cinema ever!"

She thinks her character Anna in Adult Life Skills could easily be a man. "It's just she's called Anna and I play her. She ain't called Adam and played by Andy Buchan."

Buchan, of course, plays her Broadchurch husband Mark. She tells me about press conferences where they've sat together doing press for the series. "Everyone talks to me about playing mothers and they never say to him 'you're playing a father.' My roles are listed. 'You play a lot of mothers.' Well, he plays a lot of dads. And they always go 'let's talk about the character Mark.' Let's talk about Beth. She's a person."

Would the 13-year-old Jodie Whittaker think the 34-year-old grown up version had made a decent fist of things? "Yeah, I think so. I haven't sacked it off yet."

When it comes to acting she is still happy to go out.

Adult Life Skills is now showing at the Cameo Cinema in Edinburgh and is available via video on demand.