Your car is, apart from the fact its a very nice car indeed, its part of the future history of the Roadster marque being the number 2 car, but first to be built & owned after the "Book Car" that Haynes has got locked away somewhere, & i suppose that makes it very hard to put a price on its worth.
As a car alone without its history it surely must be worth £5k plus .
whatever your future plans actually are..........put the car into storage or take it with you
i too had the pleasure of a spin in the car at Stoneleigh, awesome
cheers
andy