the Coolermaster iGreen Power 430W looks ok for that price
So does the FSP 400w for £32.49 details
Should be enough power for that system.
How much are you looking on for a case?
the Scan's 9006-C34 Midi Tower with 550W pPFC PSU at £58.69 looks intresting, have to check what make that PSU is though.
EDIT:
or the Antec NSK4400 ATX MiniTower, inc Hi-Efficiency 380W ATX12v v2.0 that psu should be fine, although as a minitower space might be a bit tight.