That's the kind of morgage we have too. Interest only. Good at the moment because the interest rate is so low, and it's a small mortgage anyway.
We changed in about 2004 as our previous mortgage had come to term and they wanted their capital back, which we couldn't do!
At the time it was more difficult to get an interest only mortgage so we were lucky.
The interest repayments can also be included in your tax return to help reduce your liability for tax, if necessary.
Scottish political mess. Is Devolution working?