just to add a few real world figures in....
at MV of £300k, assuming you want to take the max back out, i.e 85% of MV = £255k, less PP of £240k = £15k less fees to put into the piggy bank which could maybe be used to subsidised the rental for a while if you're expecting high capital growth.
With a loan of £255k at 5.5% the monthly figure would be about £1170 which entails getting a rental of about £1420 per month x 12 months, i.e. assuming no voids and at 120% rental coverage. So if the property is empty 6 months of the year you still need to be pulling in £1420 x 12. This does leave a nice £250 x 12 surplus to cover expenses etc.
You may of course get 100% rental coverage but it leaves things a lot tighter.
May be better viewed as a
BTS cut and run job at slightly below MV for a quick sale and pocket the dosh?
Some of the more experienced forum heads probably have a more accurate model for you!