It is 10pm in London and New Zealand-born novelist Kirsty Gunn has had a difficult day. "I've only just got the girls to bed," she says, guiltily.

The girls in question are Gunn's daughters, Millie, 11, and Catherine, 8.

"School's out over here, so the girls wanted to spend the day with me. Ordinarily, I wouldn't have a problem with this, but I've just returned from a teaching and reading tour of the Gironde district in Bordeaux, so a few academic deadlines for Dundee [where Gunn is professor of creative writing] have piled up.

" I felt myself getting really tense. In the end, I had to leave them to it. 'Look,' I said, 'I've got work to do.' I felt terribly guilty and, of course, once the Dundee stuff was done I sat up late with them. Being a mother and having a career's never easy."

What's this, a rare note of weakness from a woman who seemingly has everything? Apart from being mother to two busy daughters, Gunn has a home on fashionable Portobello Rd in Ladbroke Grove and is married to publishing bigwig, Granta managing director David Graham.

She is no slouch in the British literary world, of course. Her first novel Rain (published in 1994) won a London Arts Board Literature Award and was made into a film directed by Christine Jeffs. Three further novels, including The Boy and the Sea, voted the Sundial Scottish Arts Council Book of the Year in 2007, and a story collection and memoir, 44 Things, have turned Gunn into an internationally published author whose books are translated into 12 languages.

She teaches, and writes for the London Review of Books, the Guardian, the Independent and the Daily Telegraph. "I'm busy, aren't I? I can't help myself. I'm passionate about everything I do, but it is a challenge. Whenever I get on the train to Scotland and leave the girls, my heart breaks.

"Last year, I missed Millie's 10th birthday because I was at a literary festival. But what's the alternative? Being a stay-at-home mum and remaining unfulfilled creatively? That's not for me. I think I'm a better mother for doing stuff I love, like writing, because once work's finished, I return to my kids refreshed by my creativity."

Gunn, 49, has always been an accomplished multi-tasker. Long before she had children and a dream job as an author, she worked as a freelance journalist writing articles, film reviews and fashion and agony-aunt columns for publications such as Vogue, More and Brides.

"There was a time when I also worked for an ad agency. I had the Pedigree Chum account," she laughs. "It didn't take them long to fire me. I only worked in the mornings. In the afternoons, I sat in the office writing short stories that eventually turned into my novel Rain. The day I was sacked, David took me to dinner and said, 'Good, now you can finish that book of yours'. That's exactly what I did."

It sounds simple, yet it becomes clear her impressive achievements and the juggling of writing, teaching and motherhood make for precarious success. For the woman who vehemently declares, "I don't go back and read anything I've published, I don't need to" is the same woman who seconds later adds, "It's too painful really. I can't ever feel comfortable with what I've achieved. I'm always anxious about the next book or project I'm working on. My life's relentless like that."

As it happens, Gunn's next literary venture is going to make her even busier. For she has decided to uproot the family and lead them across the world to New Zealand so she can take up a six-month writer's residency at Randell Cottage in Wellington and appear at the Auckland Writers and Readers Festival next week.

"I'm really looking forward to returning to New Zealand. The feeling one gets when you fly across an expanse of blue sea to get there. One's first glimpse of the country. All those little houses scattered close to the shore which seem to strain to look out to sea and say, 'Bring me news of the world'. Just thinking about it makes me feel very intense and emotional."

And the family, what will happen to them? "Millie, Catherine and David will follow me over, which is great. While we are in New Zealand, the girls will spend a term or two at my old school, Queen Margaret College in Thorndon.

"I'm so excited about that. They'll miss their friends in London, of course, but at least we'll be together as a family. And I know they'll love Queen Margaret. It has a terrific history of encouraging students in creative arts.

"When I was there, they had the most wonderful prizes and magazines which got me writing. It was a very inspiring place for someone like me who, even back then, wanted to do nothing but write."

IT'S this displacement of self and family which Gunn admits is the downside to her hectic literary existence. Over the years, she has lived in Wellington, Oxford, Edinburgh, London and Dundee.

Asked where home is, she replies, "I don't have one. I'm a misfit in the way that people who leave the place of their birth always are. London's my home in a sense because this is where I've bought a house and raised my children. But I think that sense of homelessness is one I'll have forever.

"Curiously I had it even when I lived in New Zealand, because of my family's Scottish and English roots. When I was a girl, we called Scotland home. When I was 20 and landed at Heathrow for the first time and made my way up to Edinburgh - those experiences were like a coming home."

The dislocation of the return to New Zealand aside, Gunn remains focused on the numerous projects she is aching to get stuck into during the Randell Cottage residency.

"For a long time, I've wanted to write something about Katherine Mansfield. She's been such a big influence. When I was young, I felt her ghost haunting the Thorndon streets. And my mother was a huge fan. She read Mansfield's stories to me all the time.

"So the residency is going to allow me the space to work on that project. It's called Thorndon and I'll spend a lot of time at the Alexander Turnbull Library researching it. Rather than a fictionalisation of Mansfield's life, I think it's going to be something more personal - my creative response to her work.

"I'll also be completing a short story collection I've been working on for a while. Most of it is written. There are one or two more stories to write. It's called Infidelity. David tells me not to rush. 'Story collections aren't selling at the moment,' he says. 'Wait till you've published another novel, then you can sneak the story collection into print'."

Gunn has also got something else up her sleeve.

"A director friend asked me to write a treatment for a film. I've never done any screenwriting before, so I thought it would be difficult. But surprisingly I found it easy. That's on the backburner while my friend tries to get a producer interested. But you never know, something might come of it soon."

With a laugh, she concludes: "After all, it's not like I haven't got enough on my plate, is it?"

* Kirsty Gunn will appear at the Auckland Writers & Readers Festival, Aotea Centre, on Friday, May 15, at 5.45pm and will chair An Hour with Monica Ali on Sunday, May 17, at 10am; see www.writersfestival.co.nz