suggestions will vary, it's best to advise what you'll be using your rig for so an appropriate rig can made. I'm not from the UK so don't know how much parts cost over there and the shops but I'll just post a few suggestions below.
Intel Core i5 760
Gigabyte P55A-UD3
Samsung Spinpoint F3 1TB
Antec Truepower 550W
AMD 6870
Any 1333MHz or 1600MHz ram
also got options for an amd build with a x4 955 or x4 965 cpu
