With any bank account in the UK, the risk is that you get reported for suspected money laundering. The banks are supposed to report even a "whiff of suspicion" and are not allowed to tell the customer that they have been reported.
If I were operating a business like this, I would do it through a business account with a trading bank (not a building society), and I would make sure the bank understands the business model. That's all the bank cares about, and they ask you all this kind of stuff when you open the account.
For advice, I would ask an accountant. They deal with banks and the taxman every day, and they know exactly how the system works.
Unfortunately, doing it that way will cost a bit, because you'll be paying the accountant by the hour while you explain the subtleties of Bitcoin to him. I would consider describing bitcoins as "barter tokens" because I think they will readily understand that.
For an alternative approach, have a careful read of Nanaimo Gold's payment options page:
http://www.nanaimogold.com/payment_options.phpand see how he has managed to avoid the need for incorporation, business bank accounts, accountants, lawyers, etc., while still accepting only "hard" payment for bitcoins. Of course an accountant will never recommend that kind of approach, because it doesn't provide a slice of the pie for the establishment.
