The Capital Gains Tax on the rented properties is relatively straightforward. You pay top slice capital gains tax on the difference between what you paid for the properties and what you sell them at.
If you were using one of the properties is your main residence that stops the capital gains issue and freezes it at the time you moved in but it does raise a capital gains matter on which ever property you had been living in
I think this is going to be better referred to UK tax. I shall transfer it for you.