No, but Apple store computers will. You'll have to sign up with one of the available plans from one of the available carriers before they hand you the box.
They invented this thing called the Internet a while back, and it turns out it's pretty easy to share information with it. If you have a question, a complimentary call to the service line for that carrier will probably be right at your hand. It's not any different than how it works now with the online setup, except that the actual signup will occur in-store before you take your shiny new iPhone home and activate it on your home computer.
I imagine some form of authorization code will be printed to show the Apple store clerk, showing your plan. It'll work out just fine.
If Apple make you sign the contract in-store then they will be legally obliged to give you all the information regarding contract costs, service plans etc that pertain to the contract they are selling you. And go check o2.co.uk for that info is not a valid answer.
If the iPhone is not Network exclusive then they will have to provide you with all the alternatives and the ability to compare the deals and for you to ask the salesperson those pertinent questions. Failure to do so would leave Apple open to mis-selling contract claims. This would be costly to Apple and the claimant(s) would have the right to nullify the contract if it was found they were mis-sold and be compensated.
A case in point- It was ruled many UK endowment mortgages were mis-sold. That ruling has cost the UK banks/lenders well over a billion pounds in compensation so far (and not all claims have been settled.) Not taking into account millions issued in fines and the enormous cost of processing the claims which run into many millions
UK on-line sales are governed by different rules but you have 14 days to cancel the contract under distance selling regulations if you decide to change your mind