Use Amazon.co.uk or ShopTo.net if you want cheap UK games. But be quick, as most of them are only cheap because of special holiday promotions, not because of the cheap pound.
The usual price is ~40 to ~45 euro, about the same as importing an American or Asian game.
But now, many shops have 40 to 60 percent holiday discounts, resulting in games as cheap as 20 euro.
A few examples...
Amazon.co.uk
(shipping: add 1 euro per game, 4 euro per order)
ShopTo.net
(shipping: add 4 euro)
Give or take a euro or two depending on the exact exchange rate.
Correctly calculated examples:
29,96 for MotorStorm Pacific Rift; 23,00 for LittleBigPlanet. Order both and you only pay 48,68.
So yeah, if you look around a bit, for 399 you can now have a bundle consisting of an 80GB system, 2 DS3 controllers, a Blu-ray remote, a Blu-ray movie, LittleBigPlanet, MotorStorm Pacific Rift and Resistance 2.
Buy the actual PS3 for 299 and get the games and an extra controller from the UK.