I've spoken to LOADS of retailers in the past few weeks and it seems that unless you've ordered one and paid a deposit, you're unlikely to get on on Friday.
Your only chance is to go to LARGE high street chains that haven't been taking pre-orders and hope they have one... Woolworths, WH Smith, John Lewis, Debenhams.
I spoke to a chap who works for a large supermarket and they still have no idea if they'll receive any at all before Christmas, and he reckoned that all the big supermarkets were int he same boat. Basically, with supply outstripping demand so much, they just don't come high enough up on the list of priorities for orders.