Should i change from an interest only mortgage to a repayment mortgage?

I have 15 yrs to go on my mortgage. I have been paying interest only for the past 10 yrs.It is a low mortgage �27,000. I don't know what my cirstances will be like in 15 yrs time and don't want to leave it to chance that an ISA will pay for the capital and be left homeless. Interest rates are low just now and may continue to do so for a while. So do i wait a while longer or start paying off the capital just now and be able to own my home outright in 15 yrs time?