Another UK service which I've used myself is speedybitcoin.co.uk. As I mentioned in a separate thread (
https://bitcointalk.org/index.php?topic=247083.msg2625605), you specify a receiving address, and whenever you send a bank transfer using particular details, you receive Bitcoins at that address based upon the current Mt Gox exchange rate. Note, though, that Mt Gox prices have been out of whack since their announcement that USD withdrawals would be temporarily suspended for two weeks as of 20 June. If you give it a few days, hopefully the rate there will settle toward something closer to what it is everywhere else.