I was just about to purchase this from Amazon as the deal posted on here was very good - checked Quidco to see what camera merchants they have, and Jacobs came up - found the same 450D 18-55 non-USM IS lens kit on there for a web price of £443.00 - the Canon cashback is now extended through to January, so -£50 off - making £393 00. Quidco list a free deliver code for orders of £50 or more. PLUS 5% Quidco - I'll post if it tracks - but thats another £22.15 off the price making a total of £370.85.
Quidco had a free delivery code for orders over £50 - the one listed on this site is for orders under £50 I think, I used the quidco one and it worked fine.
the Amazon deal was poseted here: http://www.hotukdeals.com/item/252398/canon-eos-450d-digital-slr-camera-k/
Jacobs must be crackers - lol