A public fundraising campaign to save the home and garden of the artist and film-maker Derek Jarman has been launched with a deadline of 10 weeks to reach a target of £3.5m.

On one level Prospect Cottage is a small, pretty Victorian former fisherman’s house on a shingle beach in Kent, which has Dungeness nuclear power station looming over it.

But campaigners argue it is a work of art in its own right with an internationally recognised garden. It is also a source of inspiration for artists and activists and, shrine-like, a place of pilgrimage for devotees of one of the most important and influential British artists of his generation.

A photograph of Prospect Cottage in a notebook belonging to Derek Jarman, one of the objects that have been given to Tate. Photograph: David Levene/The Guardian

It was bought by Jarman in 1986. Following his death in 1994 it was carefully looked after by Jarman’s long-time companion, Keith Collins. He died in 2018 wanting the house to have a legacy, as well as a benefit to his own surviving partner.

The campaign to raise the money was launched at the Slade School of Art on Wednesday by speakers who included the actor Tilda Swinton, a close friend and collaborator of the artists, who was with Jarman when they spotted the small painted wooden house with a “for sale” sign stuck in stones.

“Derek’s father had recently died and left him a small inheritance,” said Swinton. “Life on Charing Cross road had become somewhat overstimulating and Derek was looking for a place to be quieter.”

They went round the house and Jarman quickly knew he would buy it. “Within a couple of months, Derek was taking down chintz curtains and prizing open the lid of the first of a gazillion gallons of pitch black paint with which to anoint his new kingdom.

Swinton said Jarman created a Tardis-like home which was itself a work of art. “First and foremost, the cottage was always a living thing, a practical toolbox for his work.”

Collins, when he was ill in 2018, approached his friend the artist Tacita Dean and talked of his anxieties about what to do with the cottage.

Dean phoned Stephen Deuchar, director of the Art Fund, and a plan was hatched to give the cottage a future.

The initiative involves Tate, which will look after Jarman’s archive from the cottage, and Creative Folkestone, which will oversee its long-term care, run residency programmes and organise small group tours.

Maria Balshaw, the director of Tate, recalled being a teenager and watching Jarman’s films such as Sebastiane and Jubilee late at night on Channel 4. “These films told me that there was another world and another way of seeing and thinking. I can honestly say they changed my life.”

Actor Tilda Swinton and other artists launched the fundraising campaign to save Prospect Cottage. Photograph: David Levene/The Guardian

Dean said Jarman was an artist who touched so many people in many different ways, “whether we’re stone collectors or gardeners or gay activists or just activists, or film-makers or painters … he was remarkable.”

Nearly half the money has already been raised thanks to £750,000 from the National Heritage Memorial Fund; £500,000 from the Art Fund; and £250,000 from the Linbury Trust.

That still leaves a big sum. It is “a bit terrifying,” said Dean. A crowdfunding page at artfund.org/prospect has been created with prints and works of art for sale. They include, for £25, a badge and set of stickers designed by Jeremy Deller. For £100, a Michael Craig-Martin print. And for £1,000, a limited edition print of a blackboard drawing by Dean.

Deller said the cottage gave a great insight in to what Jarman was like as an artist. “The word unique is overused, but this really is a unique environment, it’s a unique building. Within it you can see his thought processes, you can see his work and it is all in such incredible condition … he deserves to have this kept as it was.”

A deadline of 31 March has been set to raise the money and prevent, the Art Fund said, the risk of it “being sold privately, its contents dispersed and artistic legacy lost”.