A credit rating basically isn't considered for a mortgage in the UK. They will check a report, and maybe request you pay outstanding debts (I was asked to clear my CC balance before completion both times), but unless you have a fraud marker or are bankrupt it won't affect you. Mortgages are secured on the asset, so it's far less risky than a personal loan of 5x less - the bank can seize the asset and force the sale of the home (and that difference in risk is reflected in the difference in borrowing rates).