It's all about the lender, they will not lend to someone with an iffy credit rating, therefore what you are asking is "can I get the mortgage alone"? yes if you earn enough to satisfy the lender. The lender will have a primary charge on the property and will object to joint ownership on the basis that it effects their security. Forget "deeds" they are irrelevent now days, it's the land registry that matters. You can add your partner to the LR entry later but that will amount to a transfer of equity and you will have to get permission from the lender or you can do it when the loan is repaid.