Budget? If you need 4 HDMI inputs that rules out pretty-much all the all-in-one systems (which are mostly terrible anyway).
The Yamaha YHT196 is great value at £180 from Richer Sounds, but it only has 3 HDMI inputs. Next up you'd be looking at the Onkyo HTS-3505, £350 but it is a better set-up and it's got four HDMI inputs. They also do a bundle with a Sony receiver (4 HDMI inputs), Sony Blu-ray player and Pioneer speaker system for £300 which might be worth a look. Obviously you won't need the Blu-ray player if you have the PS3.