Resolved Question: Question about Capital Gains Tax?

I have inherited a flat which has been valued at £90,000 for probate.

I wish to sell it.

If I sold it for, (example), £110,000 would I be liable for Capital Gains Tax on the whole £110,000? Or just the £20,000 profit?

If I sold it for £90,000 (the probate value) would I be liable to pay Capital Gains Tax at all?

I am in the UK

Thanks in advance.

I am asking for general pointers, as I have no knowledge of this at all.
I have never owned a property before.