Hi Martin. It is not unusual for both older unfinished GTD and KVA kits to appear for sale (usually on eBay or various forums). However depending on how much of the build has been done, there is potential for a lot of updating to be carried out to meet the current IVA test requirements. Also the invoices for all the various parts used may have got lost in the mists of time. Older kits tended to use parts from multiple donor vehicles and this will now result in a 'Q' plate even if you can get it through IVA. Also a company called MDA made an excellent kit some years ago but it is rare for one of these kits (or complete cars) to come up for sale.
Of the current UK kits, both AK Sportscars and Tornado are worth looking at. AK Sportscars purchased the business of Southern GT several years ago and have further developed the kit and have got many cars through IVA. Tornado have been in the GT40 replica business for many years and have a wealth of experience.
Both these companies are exhibiting at the kit car show at the Three Counties Showground just south of Malvern next weekend (30/31 May). The venue is not far from you therefore I highly recommend that you visit the show. Also there will be a number of cars outside in the Club area, which provides a great opportunity to chat with builders/owners.
Best regards
Steve Dean.