Firstly welcome! I also noticed that about the spammer and your forum name, I wondered if you were going to keep your GT-four in the driveway of a Kerala apartment for some solace?
Also if you need a replacement pump Betsy (Stephen) on here runs
http://www.gt4-play.co.uk/which does an exchange service for the unit if I recall.
To any new GT-four owner: TCB performance is where you need to go for all things service related and for OEM bits that break, drop off or just need replacing.
http://www.tcbparts.co.uk/ The website is a bit dated, but it's functional and has almost anything you could want in terms of standard parts.
Camskill also stock a few bits, but are often quite pricey.
The rest depends on where you are in the country, as there are several specialists dotted around the UK. These garages etc can come in very handy for any big jobs or performance/restoration/aesthetic goals you may have in mind for the car.