Also, ask which types of "proof of address" they require. Different GP front desk people may ask for different things -- just yesterday one I called in my new area I moved to said that they will only accept my lease agreement or my water rates bill, but not a bank statement showing my address, nor any other bill!
You'd think all kinds of "proof of address" were equal, but I guess not at this particular surgery. So, just posting another detail that might help smooth the way.