Just come back from a little last minute christmas shopping at Asda in Poole, and spotted Guitar Hero: Warriors of Rock Solus (without guitar) for £20, which isn't too bad considering it's still pretty new. Brand new too.
Can't be sure if it's nationwide or store specific, but they had one 360 and one PS3 copy left once I had picked up mine :)
Hope it proves to be helpful, as it's my first deal I would love it to go hot!
Merry Christmas everyone!