Scholastic Book Clubs have £5 off orders over £35 with promo code xmas5. It's a friends & family code but specifies that it can be shared. Delivery is free over £25.
[[http://clubs-shop.scholastic.co.uk/}}
They have some great offers like all for Twilight books for £15.99, three Wimpy Kids for £9.99, and lots of good things for £1.99 too.