I'm not aware of the average prices for components in the UK, but judging on the parts you've selected, it seems to be a very good budget orientated build. Also, take the advice "thenightwatchman" has given you, that build will run you at max only 450-500W's, 550 if overclocking, so go with a PSU from XFX, (the one you have in your current build is good), and just lower its wattage. You'll save a few cents.
Other than that, looks great! 9/10.