If you're thinking of buying a new phone, this could be of some use (although might not work in every store, worth a try if you're thinking of buying from Phones4U anyway).
Instore only - I recently bought a cheap £5 Motorola F3 phone from Phones4U in Aylesbury. The sales guy asked me if I wanted a years insurance for £30, of course I said no based on the value of the phone. He then offered me a couple of cheaper prices (half price etc.) before just saying he'd just give it me free. Seems like a good deal to me!
Chances are they may well offer something similar on all models, bit of experimentation needed I guess. Only thing to watch out for is (I think) £10 excess if you need to claim.