There'll be a spate of 'Don't buy GSF' posts along soon, in the mean time
Rich recommended Aldershot Car Spares (haven't got araound to trying them myself yet.
There also GolfTek in Wrecelsham (sp?) in the little industrial estate by the side of the snow 4 boats shop (or whatever it's called these days), they've had my car for work and I'd give them an average. But he specialises in breaking Mk2 golfs, and has parts everywhere, certainly worth a ring.