In reply to:
Just dawned on me that i pay through direct debit via bank account monthly
Are you talking about your Phone Bill or your Internet Access?
If Internet Access, you will have to change to 'blue bill' billing if you take up any of the upgrades, but you must stress you wish to remain on monthly billing, otherwise it may default back to 3 monthly.
If you are referring to telephone bill, then you should be alright, but I would still stress you wish to retain this, just to be on the safe side.
I found calling 0845 6007030 best for sorting out all this; press 1 for the Home option, then Option 3 and Option 2, and you 'should' get a UK operator.