As much of an AMD fan I am, I simply cannot recommend an AMD system for a desktop/full sized laptop at the moment. Only the fusion APUs (BRAZOS) at the moment is worth the money when you take the competing Intels into consideration.
I recommend the core i5 2500K that you have chosen, double tick there.
4 gigabytes of RAM is good enough for some gaming at the moment, the G-Skill Ripjaws X series at the moment seems to be quite good all things considered. Something like this should be good http://www.overclockers.co.uk/showproduct.php?prodid=MY-057-GS&groupid=701&catid=8&subcat=1517, perhaps going with the blue one on the same page may be a little better due to tighter timings but generally the difference will most probably not be noticable
For a Power Supply, the 1000 watt is probably overkill unless you are expecting to put in another GPU in crossfire. I'd recommend for this system a 650 or at the most a 750 watt PSU. For a guide as to how much power you need take a look at the antec PSU calculator http://www.antec.outervision.com/. Don't go with the GS series from Corsair, go with the TX, HX, or AX series. TX is the budget range non-modular, same internals to the HX and the AX is like the "extreme" version. Most of the high quality PSUs are made by Seasonic which OverClockers does not seem to stock! http://www.overclockers.co.uk/showproduct.php?prodid=CA-037-CS&groupid=701&catid=123&subcat=1084
AND a GRAND total of 1132.46 pounds. You could easily push this closer to budget limit by going with an i7 2600K instead (there is not much performance difference between this and the 2500 though), getting a BluRay Burner instead of the DVD, or going with an 8GB kit of RAM.