For REVO there is Votex in South Cheshire. Have read some favourable reviews on their service.
www.votex.ltd.ukAwesome GTI in Manchester do the APR maps and know the model inside out.
If you want a Superchips map then i can recommend the blufin unit and it can be uploaded from the comfort of your own home.
JKM performance in Portsmouth were the cheapest i could find at £390 including delivery and it arrived the next day.
There are plenty reviews on this site about each option but recommend staying with one of the proven tuners rather than taking a cheap option. Your choice ultimately depends on how you want your power delivery. The bluefin remap i have delivers the power very similar to stock, just more of it. The major boost in power is also where it is required, i.e. in the overtaking band.
The other consideration i took when choosing which map was how far you want to modify the car. If you intend to upgrade your exhaust and intake, then a remap like revo uploaded by a proffesional would be better as they can do pre and post remap diagnostics on your car to adjust it better to match your modifications. It's much harder to do this with the bluefin unit.