Consider the metalsub XRE 500. I think in the UK they'll cost about £150 and it puts out 500 lumen, which is enough to use as a primary torch for most of your diving. The quality of the manufacturing is also pretty much unbeatable.
The only other option that really springs to mind if you want a good dive light for about that price is to look at the greenforce ones and see what you can mix and match for a good price. They don't really have a 500 lumen head that you can compare to the metalsub but for a bit more money you'll be able to put together something around the P7H head that should fit in the £200 range. The advantage of the greenforce is that they're modular and you can upgrade it later if you want. Scubapro also has a cheaper rip-off of the greenforce lights that you could look at but I have no experience with them to tell you about their quality.
In any event steer away from Suunto lights. Too many people I know have had bad experiences with them. The battery contacts aren't robust enough and they often flicker or even fall out under water. Also in my experience lights from Mares, Cressi, Tusa, UK and all that plastic crap just doesn't have the life-span you would expect for the price of them. This really is one case where buying too cheaply can be more expensive in the long run. The quality of the housing is just as important as how much light it pumps out.
There are probably some other good lights on the market besides the ones I mentioned but the metalsub and the greenforce are ones that I can recommend based on personal experience.
Good luck.
R..
