Now, this may or may not work, so dont beat my down in flames if it doesnt!
Referring to my last post where you get £20 off £40 as seen here: http://www.hotukdeals.com/forums/showthread.php?t=36978
Thats £20 off the Xbox 360 premium pack, making it £259.
You currently get 11% through quidco, 11% on £259 is £230.51
Delivery is free, so seems like total spend £259, plus the £28.49 that should track in Quidco.
Now, like i say, this may or may not work, depends on whether the vouchers are honoured and whether Quidco tracks. But could be worth a shot if your buying an Xbox 360 anyway?