It depends on quite a few things. Over how many years would the mortgage be? Interest only or repayment? Have you established whether you can get a mortgage- I'm assuming that in 25 years (the usual term) you'll be relying on a pension
the usual deposit is 10%so 19k
or 20% 38 k - the rates of interest are lower for higher deposits( lower risk)
so interest only on £170k at 5% ( high) is £3800/y or just over £300 / m
add in the repayment bit - and they will probably want the mortgage to be paid off before you are 75 ... say ten years which is £17 000 a year - another £1500 a month - hmm gthat is quite a lot
but that depends on a lot of things
you can see why not many pensioners have mortgages .....