altho I am not keen on ABers not answering the question and then asnwering something else
I think you should go to a will-writer, tell him what you want, get a will, and er wait
generally you should minimise what you bind your successors to do when you are gone
for the CGT calculation as Ubasses ( my fave ! hi Ubass!) has said, it is the value on the day of your death against the later sale value, - divide between heirs - knock off £11500 or the then CGT allowance and pay tax on the marginal rate of each one ( 18% for lower rate payers and 28% for higher rate) - they will be liable for that - your estate will be liable for IHT if any
I dont see that it is your role to minimise their CGT
[in my case someone said - your heirs are waiting for you to die and then sell everything at a market value loss and geet their hands on the moolah as soon as poss! I very nearly said - how true! how true!]