I'm meeting rising Scottish star Joanna Vanderham in the restaurant of a noisy, almost too fashionable central London hotel-cum-media hangout and we bump into each other in the foyer.

She is hard to miss, tall, with long blonde hair protected from the rain ahead of our photoshoot, and a shopping bag with a change of clothes for the shoot.

By the time we reach our table, the conversation is already flying from subject to subject. Vanderham's acting skill is called for when our food arrives. She has ordered yellowtail, grapefruit and jalapeno - which looks, to the very untrained eye, like three small slices of slime covered in orange juice on the tiniest of small plates. She doesn't bat an eyelid. No trace of surprise. She's clearly good at this acting business.

This is set to be a big year for Joanna Vanderham, who was born in Perth and brought up in Scone. At the age of 24, the star of BBC1's The Paradise and Dancing On The Edge is looking to buy her first flat. "That is where my head has been at since the start of the year." She will, however, miss her flatmate's record player, but intends to move "just down the road" from her current flatshare in East London.

If this is set to be a big year personally, then professionally, Vanderham is also taking control of a career that began with a lead role in Sky1's stylish 1960s drama The Runaway, opposite man of the moment Jack O'Connell, when she was still in her second year at the Royal Welsh College of Music and Drama.

"They wanted me to come back and graduate, so they graded The Runaway, to give me enough credits to pass the year," she recalls.

And did this impressive piece of coursework pass muster? "I got a first, obviously!" She doesn't mention the Emmy nomination she also received aged just 19. Modest about her own work, full of praise for her co-stars, and clearly thrilled about the direction her career is going next, Vanderham is engaging company.

After her breakthrough, the big roles continued to arrive with a regularity that could have infuriated her peers - from Young James Heriot straight on to a film debut alongside Steve Coogan and Julianne Moore in What Maisie Knew. The lead role in a cast including Chiwetel Ejiofor, Jacqueline Bisset and John Goodman in Stephen Poliakoff's jazz age masterpiece Dancing On The Edge was another giant leap forward, while two series of costume drama The Paradise, in which she played the central character, Denise Lovett, won further acclaim and a primetime Sunday night audience.

After that buttoned up role, Vanderham was looking for some grit. "And I think I found it," she says. "I had such a great time, I can't stop grinning about it."

We are here to talk about her latest BBC drama, Jimmy McGovern's Banished. The series, which also stars Russell Tovey, Myanna Buring and Julian Rhind-Tutt, is a fictionalised account of the lives and loves of the first British convicts exiled to Australia in the 1780s. Another period drama, then, but with none of the manners, fine costumes or elegant surroundings.

Instead, Banished is set in a makeshift camp on a strip of sandy land in New South Wales, between the impenetrable Aussie bush and the Pacific Ocean. Vanderham plays Karen 'Kitty' McVitie, a young housemaid convicted of stealing from her master but spared the hangman's noose.

"Kitty's journey really intrigued me. I had no idea what to do. Ever. And I think that is how she felt. Kitty, essentially, has to survive and it is her inner strength that drew me to her."

Her character's survival instinct leads her to form a relationship with a soldier, Private MacDonald, as she begins her sentence. But she also catches the eye of brutal Major Ross. "I think the audience will be debating her decision," says Vanderham, before describing the potential awkwardness of love scenes.

Although there were what Vanderham artistically describes as "elemental issues" (Jimmy McGovern later confirms that it "pissed it down" for the first week), the two-month stay in Sydney was a blast.

"I learnt after my first two jobs that working isn't real life, it is like an interlude in your real life," she says. "For The Runaway, I went to South Africa for three months and rarely spoke to my friends or family. I was in this bubble. But that is an unhealthy way to approach this lifestyle, and leaves you feeling very alone when it ends.

"So in Sydney, I knew I needed to stay in my life. I was there to work, but I also had an amazing time and was always in contact with home. I think that is the way to stay sane when you are away for so long."

So what constituted an amazing time in the renowned party town of Sydney? Her face lights up.

"A lot of the company were very health conscious while we were there. There was lots of yoga," she says, before grinning broadly. "But there is a pretty good scene out there. We explored that quite a lot. It was mainly me and Russell Tovey. By the end we knew all the main bars and clubs.

"We ended up seeing quite a lot of theatre and cabaret, so we tried to stay cultured as well as drinking as much as we possibly could!"

This summer, we will also have a chance to see Vanderham take on an iconic role in a new BBC1 adaptation of The Go-Between.

"I hadn't seen it before, so I could put my own interpretation on it," she says. "But after I finished filming and went back up to Scone to stay with my mum, we bumped into one of her friends, who told me: 'for our generation you will never be her!'"

For Vanderham is playing Marian, or, as the character is known to anyone who has seen the 1970 film classic starring Alan Bates as 'The Julie Christie Role'.

"I just thought it was a gorgeous role and some exciting co-stars. I now realise I will have this comparison hanging over me," says Vanderham.

Still, the production did have its upsides, not least in allowing her to meet Jim Broadbent who was "as gorgeous as you would imagine. The kindest, sweetest man. I'd made banana bread that day, so hopefully I made a good impression."

Then there was the costume. "I wore an original 1900 macramé dress in pure white," she recalls. "I didn't think it was going to fit as they were much smaller then - it was a 22-inch waist, and mine is 24 and a half - but they added an extra panel, and, oh gosh, it was a thing of beauty.

"Then, of course, I walked into a door handle and ripped all of the lacing on the way to the set. I felt I had blasphemed. But it was a privilege to wear it and show it off. The director Pete Travis even changed an entire scene from being at a dinner table to outside in the garden standing up because he wanted to see my full dress. It is a very good dress!"

So busy has Vanderham been in the last few years, that when we rewind to the beginning of her journey towards acting, and ponder why she became an actor in the first place, she struggles to answer.

"I started when I was about nine in the drama club for kids in Scone," she says. "I've been thinking about this for a while. I watched a really cool show with Judi Dench and she talked about someone saying to her, 'you need to decide why you want to act'.

"I only watched this the other day, but it has been playing on my mind. My answer is, 'I dunno, I just do'. But now I feel I really ought to figure out why. Because if Dame Judi had to figure it out, then we really should follow suit."

One answer, dredged from the memory bank, involves a chance to prove her older sister wrong. "She had a video camera when we were growing up and wouldn't let me be in her video. So part of me thinks that maybe there is an element of proving I can do it - 'I will be in someone's video!'"

Instead, it seems, that Vanderham simply decided not to stop after studying drama for standard grades, carrying on to do highers and advanced highers. "I must have had a moment when all my friends were applying to university," she says, "because I downloaded forms for 12 different drama schools. I was only 17, so my mum had to sign everything."

There was no great discussion, no attempt to dissuade the youngster from following this path. Instead, Vanderham recalls missing at least a day every week of her final year at the private High School in Dundee attending auditions, each time accompanied by her mother. "The only thing I couldn't do was my monologue in front of her. There is something more intimate in performing in front of people you know.

"But my mum is my angel. She got into Rada in the 70s, but her dad advised her to get a degree first, and said if she still wanted to act, she could do it afterwards. So she went to medical school and was a university lecturer and still does presentations all around the world. She is an incredible public speaker, and has said to me that that is her performance. You know how Beyonce has Sasha Fierce? My mum must have her alter ego as well."

As well as visiting her father who lives in Portugal, Vanderham gets back to Scotland frequently. What does she miss? "If I could bring my dog here, that would be perfect," she grins. "She is a springer spaniel and when she was little, she ran into a wall, so she is not quite with it. Her name is Flop. We all disagree who named her, because nobody wants to take responsibility for such a shit name. She never learned to come back when we call her, because we didn't want to say her name too loud!"

The film and TV flops don't appear to be coming Vanderham's way either. Having tasted film success in What Maisie Knew and with a good run of big television drama under her belt, Vanderham is taking stock and looking for her answer to the Dench question: why she wants to act.

Her quest is taking her back to her first love. "When I went to college, I wanted to be a stage actress. I found screen classes really hard and didn't believe I could do it," she says. "So all the work I have been doing so far has been confusing. In my heart and soul, theatre is where I want to be.

"And I am terrified of going back. What if I am not good enough? I have all the fear engulfing me but every time I re-read the script I can't wait to do it."

It's hardly surprising, for Vanderham will be joining the Royal Shakespeare Company this week, to begin rehearsing Othello opposite Hugh Quarshie. And her role? Desdemona.

"Not a bad start, is it?" she grins. "And Lucian Msamati is Iago, which is the first time they've cast a black actor in that role. So that racial dynamic has a whole extra level.

"This will be the longest I will ever have done and the biggest theatre I have ever played. I am more excited than I am scared. It is a long career, which is why I want to do this RSC run. I want to get a real grounding in the industry I love and want to be in until I die. So no pressure!"

Unlike so many of the current crop of talented British actors, her sights are not trained on LA. "I have just done another film, When I Was French, with a much smaller budget and had a phenomenal time. I love it, but if I am honest, I feel like I would want to do films to further my career.

"If I could have Kate Winslet's, that would be great. I looked at the stepping stones of her career - but she did two films then Titanic, which made her hugely famous. So I've already missed that one.

"But I don't want to just make films for fame's sake - I want a good story, it has to be classy. Maybe we should talk after I have done Shakespeare, because that is my only focus at the moment."

And so begins an exciting new adventure in a career we may just be following for many years to come.

"The RSC feels like the right the next step," she says. "That is my summer planned. I'll be in Stratford, and hopefully I will have a flat by the time I get back."

Banished starts on BBC2 on March 5