I've just been comparing pre-order bonuses in the UK. This is what I have found so far:
Amazon UK - Harley Quinn DLC
Game - Red Hood DLC
Game - Pre-order with branded console for Scarecrow mission pack
Tesco - Waynetech Booster Pack DLC
Tesco - Special edition which includes "Batman Controller Customisation Kit when you pre order Batman Arkham Knight. The kit includes a Batman silicone controller skin, lightbar stickers and thumb grips. "
Are there any other offers in the UK?