Borrowing someone elses maths and adjusting:
6.5% of 1,000,000 is £65k.
So for 600K this is £39k
£5,434 of that is not taxed, so £5434 (more if your allowance is higher).
£2,230 is taxed at 10% so £2007
£32,370 is taxed at 20% so £25068
Leaving £32505.80 or £625 a week.
Would use £60k to clear current Mortgage and rent house out at around £800 month. Assuming charges and 40% tax thats £480 set aside £180 for contingency and thats another £300 month, £3600pa , approx £70pw.
Leaves me £340k for a new house and car plua setting it up as I want it.
Result is 2 houses no Mortgage and around £700 a week for food, utilitys and spends.
If renting is to much hassle then can clear £150k profit on current house and invest that.