The search function would help you answer these.
But...
Firstly - if you get a 52 plate it will be a JDM (Japanese Import). 03 was the first UK cars.
03-06 tax is £250 ish (cant remember exact figure)
Only 2 UK specs - GT and non-GT.
GT included Cruise, Leather Seats, Uprated Bose stereo, Rays alloys (on early cars).