Something like going to Aminet, you mean? :-D
For Amiga shops they're all mail order these days, and the ones with the largest stock arn't in the UK. Amigakit.com is in the UK, Elbox & Vesalia in Germany keep a stock of new stuff (but it's pricey). Steer clear of Analogic (UK).
For A1200 accellerators keep an eye here, on Amibench.com and ebay (be sure to search for stuff 'available to the uk' as again much of the stuff is in Germany). You won't be getting your hands on my nice 8Mb memory expansion in my A1200 though :-P (bought it from another member here).
Eyetech, creators of the new Amiga A1 motherboards, arn't far from you either ;-)
