No worries. I work in Dorking, but live in Woking...
After all their positive feedback I took my car to R-Tech about a year ago for a stage 1. Couldn't be happier with the results.
The cat back exhaust probably wont give you any performance gains at all, just a better sound - someone may want to correct me here...
If you can stretch to it I'd personally go with a turbo back system - with an upgraded cold air intake you can then probably go to stage 2
Edit: The reason I'm saying turbo back, is that the price on the tutts website is for cat back only