If you have already decided that you want to have your current account and mortgage with the same bank, you will have to decide based on either the current account offering or the mortgage offering and just put up with whatever they offer for the other.
(BTW, I dont understand why you feel a need to do this)
Mortgages are much harder to get than current accounts and a poor deal on a mortgage will cost you far more in the long term than a poor current account.
Therefore, you should get the mortgage wherever you can, and move your current account to same bank.
It would be foolhardy to move your current account now and deicde that this is the only bank you intend applying to for a mortgage.