I think you have done very well to be fair. That is assuming you are set on SandyBridge I think that is the best you are going to get for the price anyway. The case doesn't come with a front fan, you might wanna stick one of those in but other than that, a decent spec.
The problem is that you have used a GTX460. I fully understand how hard it is to fit a 2500k into a budget like yours and I think you have done well as I said before but if you went with an AMD system with an AM3+ mobo you could probably be looking at 560Ti. How likely are you to be able to make a big upgrade (at least £150) in about 6 months - 1 year?
This was regarding the Intel build.
About AMD...
I think you could get a 560 Ti in there, it is quite a bit better than a normal 560, definitely worth the extra £10-£15 especially as you haven't maxed out on the budget. I have
this one and it is pretty good. Stays quiet even when playing games on maxed.
All depends on when/if you plan to upgrade in the near future..
3rd edit on this post: Basically I was at this price point a few weeks ago and if I had it again I probably would still go with AMD. It isn't struggling and now there are affordable AM3+ mobos out to tempt you even more which I didn't have. I haven't really tested it as I am waiting for the summer sale on steam to buy some games although I have MW2 and it runs everything completely maxed and recording with fraps at 1080p fine. I basically have the spec you suggested with a lot worse motherboard and a 560Ti.