dream on guys. few people has already reported you only get the £35 quidco cashback if you actually sign up the 18 omnths contract. £100 if you are very very very lucky. If you plan to unlock it, you don't get any cashback.
some early stage buyer when it's still £269 claims to get £60 quidco from CPW (still end up costing £209). Since then everyone been getting £20 only (official amount from quidco). I know we're hoping for £100 quidco from O2 but quidco did say clearly it's only £35 for iphone.
So as a summary, you get a max of £20 quidco buying from CPW or £35 from O2 and they are not guaranteed unless you accept the 18months contract, otherwise most likely you get 0 quidco