UK cars are *much* rarer, and I doubt you'll find a nice one for your budget. It's a well-known fact (on this site) that UK specs are cheaper to insure. The risk factor is much greater for the insurance company on an import for a variety of reasons (cost to repair is generally higher, maintaining the car is considered more expensive, lower prices mean the type of people buying are usually higher risk).
However, you'll get more for your money with an import car as they don't command such a high premium in the sales arena.
With your budget I'd forget about a UK spec and find a decent spec import TT, then get quotes from companies like Sky Insurance, Lancaster, Adrian Flux etc. You'll need to phone them though, don't go online to do it. Make sure you declare all mods too.