If you purchase a house for £750,000 over 18 years that would take you to state pension age
you'd have at 4.85% a repayment of £2085 monthly - if you're allowed to overpay by 10% that would mean you could pay and extra £208.5 each month raising the repayments to £2283.5 each month - you'd repay the mortgage 29 months early and save approx £22,000 interest
If though you took a 12 year mortgage you'd repay £2,758, you'd save £54,000 interest compared to the first scenario
You're 49 or thereabout now
Id want my mortgage paid off at 61 year old
I don't see how you're going to pay a mortgage at 69 on an old age pension without working and without private pensions to speak of
if you're paying 37% tax on what you both earn, then you're combined income is £7500 per month so paying the mortgage over 12 years would leave you with £4742 to live on
The question is can you live now without the £500 per month or when you are 60 will you be happy to sell the house and move else where if one of you has to stop working
Its a gamble