I had a Swift for a day at the Ring a few weeks ago, absolutely hilarious little cars. I'd have one in a heatbeat.
Aside from the obvious choice of a MK5, thinking about stuff I regularly see that doesn't blow up:
FWD
Megane
Clio (you might just squeeze into a 200 Cup at £10k?)
Integra Type R
1.8T'd MKII Golf
Swift
Ex-Mini Championship race car (quite often see these and they go for daft money)
205 GTI
RWD
MX5 (loads of turbo/supercharged ones about)
E36/46 M3
944/968
200 SX
RX8
Caterfield
S2000
Elise
I suppose it depends what you want out of it? An out and out track car or something capable that you can still travel distances in without wanting to burn it??