this. you buy the module + the map and upload the 133 map, they are renault specialists from the netherlands and are the go to company for cliosport.net, you car will no doubt be standard or close to standard in terms of engine and breathing so this will be the best option and perhaps the cheapest as you can sell the RS tuner box on once the map us uploaded for 50-80 pounds.
your second option would be to call mike @ MWN in staines (Michael Woodford Motorsport). he has a very good reputation and has built a few epic cars in his time, there is also 519 automotive.
i hope you realise being a small 1.6 N/a engine, you're not going to get a realistically noticeable increase in horse power. the only thing that'll change is the driveability of the car, better throttle responses etc
hopefully dazza or lewis sees this and can point you in the right direction of some other good places in your londonshire area! they are from around the bromley area i'm sure