They are very good psu's. Seasonic built with 540w available across the dual 12v rails. The thing is that another £8 buys you the very good, fully modular Bitfenix Whisper M 550w which has a longer warranty at 7 years. Review here.
My basket at Overclockers UK:
Total: £88.49
(includes shipping: £10.50)
Thanks for the feedback, went ahead and ordered the Antec, seems like a solid unit.