These mortgages are now only offered with very strict criteria and aren’t available to everyone. With an interest only mortgage you only pay the interest charged on your loan so you’re not actually reducing the loan itself. You’ll need to have a feasible repayment strategy in place to repay your mortgage at the end of the term. For example investments and/or savings plans. Lenders will want to see proof of these.
The advantage of an interest only mortgage is that if the savings or investment plan you choose performs well, then you could pay off your mortgage earlier compared to a repayment mortgage. At the full mortgage term there may be a lump sum available after the mortgage has been paid.
The disadvantage is that very few investments are guaranteed to repay your mortgage in full. If your savings or investment plan doesn’t cover the full amount, you’ll be responsible for paying the difference.