Your monthly payment covers both the amount you’ve borrowed and interest. So as long as you keep up your payments, your mortgage will be paid off at the end.
Interest only mortgage
Your monthly payment only pays off the interest. You’ll still need to repay the amount you borrowed at the end of your mortgage and will need a separate plan in place to do this (such as an investment or endowment). We may limit the amount allowed on interest only.
You can choose to pay part of your mortgage as repayment and the other part as interest only.