Nicole Farhi is a household name in British fashion, having been in the business since the 1960s. She started out in Paris before moving to London, but the cutting room was not where Farhi saw herself forever; sculpting in her studio at home was where she felt happiest, and still does today. 'I was not entirely satisfied with a life dedicated to fashion,' Farhi admits. 'I wanted to express things other than just making clothes.'

The transition from full-time designer to sculptor was very gradual. 'I had waited a long time until I could say goodbye to fashion and dedicate the rest of my life to sculpture,' she says. It wasn't an easy decision to make. Farhi would take one day a week off fashion and spend the weekends in her studio, and after 35 years of juggling the two she became a full-time sculptor. She insists that sculpture was always more than just a hobby, which is evident from the way she talks about her practise: 'it's very absorbing, like meditation'.

The paths her career has taken may not seem worlds apart – both require a hands-on approach to designing and making – but she feels that they bring her entirely different kinds of fulfilment. 'I enjoyed the pace of fashion where every six months you start again. I liked that challenge.' But the solitude of the studio was a welcome change. 'I love to face my own thoughts all day long and not having anybody to talk to,' she confesses, but that's not to say Farhi has always enjoyed working alone. If it wasn't for the deep admiration she had for her team (many of whom had been with her from the very beginning of her career at French Connection in the 1970s and moved with her when she founded her own label in 1982), the shift to full-time sculptor would probably have happened sooner.

Sculpture has been a large part of Farhi's creative output, just not as widely publicised as her achievements in fashion. 'Sculpture is not really new to my life,' she explains. 'It was really what I wanted to do one day completely.' Her work has been exhibited at venues including Beaux Arts and Gainsborough House, and she's a member of the Royal Society of Sculptors. This summer she makes her debut at the Edinburgh Art Festival with a solo exhibition, Writing Heads at The Fine Art Society, which contains 25 clay busts of her favourite 20th-century literary figures, from Oscar Wilde to Joan Didion. But these are by no means the grandiose busts you might expect to see of such acclaimed individuals: they are all under 20 centimetres high.

The miniature series came about almost by accident, when she began making the busts as gifts for her husband, playwright David Hare, whenever he opened a new production. Farhi marvelled at the enjoyment she found in working on such a tiny scale, so much so that she revisited the idea whilst working simultaneously on a large-scale work, Folds. 'For my own pleasure, I decided to go back to the tiny little busts as a release from the large casts,' she says. Gradually they became a series of 25, a number she felt satisfied with. 'After the 19th-century authors I did for David, I thought I'd do writers that I had read, starting with the books that I loved reading when I was growing up in France: Simone de Beauvoir, Camus, Duras, Cocteau. While I was doing Simone de Beauvoir I was thinking "well what about Camus?" So one called for another each time.'

Whilst the busts themselves are a highly personal exploration of Farhi's own memories and relationships, Edinburgh is a place that holds poignancy for her too; she was a close friend of the late Eduardo Paolozzi, the city's master sculptor. 'Eduardo is in my mind always. He believed in what I was doing, and it was a wonderful chance in life to have met him and be his friend,' she reminisces fondly. 'I was very lucky and I cannot ever forget that,'

Visitors will get a sense of his influence upon her life and work, as she elaborates further on the exhibition's content. 'I did a portrait of Eduardo when he was alive, and of his hand, so I think we're going to show those. I had gone to Edinburgh with Eduardo a couple of times so I'm very happy about going back to his home.'

Nicole Farhi: Writing Heads, The Fine Art Society, Dundas Street, 25 Jul–31 Aug, Mon–Fri, 10am–6pm, Sat, 11am–4pm, free.