Hi,
Welcome to the club!
Well Adam I hope you get close to that, as an idea I spent 18 months looking at westfield's and my car was £10k. 1.8 Zetec, SeiW, mt75 gearbox, full weather gear, doors, screen, 4point harnesses, RAC bar, adjustable shocks all round, discs all round, 2005 car with 1864 miles on the clock. I've done a lot to it and spent a few grand on seats, wheels, QRS steering wheel and lots of carbon fibre.
I do think you'll be far better looking for a really good crossflow, seen a few nice ones for that price. Looked at reasonable 2.0 vauxhall's for around £7k. I had pinto power pre Zetec and that was also a vary good engine, 2.0 injection... Pretty much a standard engine with 105bhp... Normal road driving was perfectly fine, engine parts were cheap and easy to find/fit and a whole engine is pretty cheap if you need one. I turbo'd mine and got 162 BHP!!! I then found out big turbo's don't work in seven's (was a Robin Hood) and sold it to by my Westfield.
Feel free to PM if you think I can help at all.