AS she strolls into The Herald offices wheeling a suitcase behind her, Kirstie Swain looks every inch a woman going places. When we meet on a windswept Monday morning, the screenwriter is en route to London fresh from visiting her parents in the Berwickshire village of Ayton.

The point I am labouring (badly) is that this is a woman going places in more than simply a geographical sense. This week will see her debut original series begin on Channel 4 – a six-part comedy drama, Pure, based on Rose Cartwright's acclaimed memoir of the same name.

Swain, 35, currently has several TV projects in development including working with Sid Gentle Films, which produced the hit drama Killing Eve, and Synchronicity Films, the Glasgow production company behind recent BBC thriller The Cry. Not bad going for someone who "fell into" scriptwriting.

Pure centres on Marnie, a young woman with a severe and undiagnosed form of obsessive compulsive disorder, nicknamed "Pure O", which takes the form of intrusive thoughts involving graphic sexual imagery coupled with overwhelming self-doubt.

After a speech at her parents' silver wedding anniversary in the Scottish Borders ends in an embarrassing calamity, Marnie – played by newcomer Charly Clive – boards a coach to London where she finds an eclectic band of kindred spirits.

The cast includes Peaky Blinders' Joe Cole and Kiran Sonia Sawar, who previously graced our screens in Black Mirror, as well as Two Doors Down stars Arabella Weir and Doon Mackichan.

When approached by TV production company Drama Republic to work on Pure, Swain felt an immediate connection to the subject matter. "They sent me the book, I read it and said f*** out loud loads of times because a lot of it resonated with me," she says.

There were, says Swain, echoes of herself in Cartwright's experiences – a rural upbringing, crippling anxiety, the burning desire to write and running away to seek adventures in the big city.

"The whole idea of cyclical worrying," she says. "I got that completely because I have always been a massive worrier and I was a really anxious child. It made me think: 'Oh, all the anxiety has been worthwhile because now I get to write something …'"

The eldest of three daughters, Swain grew up in Ayton near Eyemouth. She has vivid memories of the military aircraft that would frequently scream low overhead on training exercises throughout her childhood years.

"I used to be so anxious," she says. "I wonder if it has got something to do with the fact that we lived in this area where they used to fly jets over? It sounded like it was tearing a hole in the sky. I remember ducking quite a lot as a child. I think that might have instilled something in me.

"We had this dog called Abi that would wet itself every time it saw a man. I feel I was like that until the age of 28. It wasn't like a switch flipped: it took that long to know myself."

This shyness and anxiety is something Swain refers to throughout our conversation. "I always felt a bit like an outer calm but an inner cyclone," she says.

Television loomed large from early age. She recounts childhood evenings sneakily watching everything from EastEnders to Eurotrash in her bedroom.

"I bought this little black and white telly at a silent auction for £1.74," she says. "When my mum found out that I secretly watched EastEnders she grounded me." Swain breaks into a cheeky grin. "I then wrote an episode of EastEnders [in 2012] – the ultimate act of payback."

Her career ambitions back then were a tad more leftfield. "I wanted to be an opera singer. I would sit in my room singing Part of Your World from The Little Mermaid and Phantom of the Opera. I remember running down a dune on holiday in Ireland singing Think of Me.

"I always wrote short stories and put on plays. I loved English and reading. Even at primary school I would ask if I could take my jotter home and finish a story.

"Screenwriting suits me. I love dialogue. Having been quite a shy child, I thought a lot about how people speak. The fact that I felt like I couldn't speak made me listen to others. I love listening to people, how they speak and the rhythm of their sentences."

Swain excelled at sport too. "I played a lot of badminton," she says. "I was in the Scotland squad. I got quite into things – if I did something, I did it properly. I was a swot and probably playing badminton in a school hall instead of drinking cider with my friends on a bench in the park."

Her parents are retired teachers who would spend weekends ferrying their eldest daughter to badminton tournaments, then later back and forth to Radio Borders where she co-presented a school magazine programme called Class of 2000.

"I wrote this thing that was inspired/ripped off from Have I Got News For You called The News That Didn't Make The Headlines," she recalls. "It was just funny news and I would read it out."

After studying English language and literature at Glasgow University, Swain spent a year working for a local newspaper before joining a corporate video production company. "They told me they did documentaries – it turned out they had done one," she says. "I felt like I had been tricked."

With hindsight, she is grateful for the doors it opened. "It was actually the best job I could have had because they really invested in me. I learned so much there. I was able to write stuff, produce it and see it made. That was great – almost like a crash course."

Her employers paid for her to do a PGCert Screenwriting through Screen Academy Scotland at Edinburgh Napier University. Swain penned a sitcom pilot that was shortlisted for Scotland Writes in 2009 – a competition run by BBC Writersroom.

That success bolstered her confidence. Soon afterwards she quit her job and moved to London. Swain recounts this part of the story almost apologetically as if embarrassed by the cliche of the young woman who arrives in the big smoke to find herself and make it.

And make it she has. Even if it took a bit of hard graft. "I was so determined I was going to be a writer that I didn't go down [to London] with a job. I had to do a lot of freelance stuff and ended up working in a deli. The person who ran the deli, his wife was a TV director, and she optioned my script."

That script, its early incarnation known as Big Fish, has since evolved into a drama called Gutted. Currently in development with Synchronicity Films, Swain describes it as "a female-centric relationship thriller set in an east coast fishing town."

She is also working with Sid Gentle Films on a project called Man Killers about the women of the Scythians, ancient Siberian nomad-warriors believed to have inspired Greek mythology about the Amazons.

Then there is Ladybaby, a comedy drama set in Edinburgh about a 35-year-old stand-up comic who is tracked down by the daughter she gave up for adoption at 15. Swain has that one in development with Kudos, the production company behind Broadchurch, Grantchester and Tin Star.

While researching it, she plucked up the courage to try stand-up herself. "The first thing I did was a five-minute impression of my dad who is from Northern Ireland. That was my stand-up routine and people laughed. I just kept doing it."

Swain will perform her first paid stand-up comedy gig – supporting Ken Cheng – at Hemelvaart Bier Cafe near her family home in Ayton next month.

She admits to some trepidation. "My mum and dad have never seen me do comedy and they are coming to watch," she says. "It is going to be a big family outing. I am very scared. It feels like an anxiety dream.

"It couldn't be a worse set to do in front of my parents because one joke is about my dad, one joke is about my mum and the rest of it is about how I have sex. It is going to be weird."

Pure starts on Channel 4, Wednesday, 10pm