If you dispose of UK residential property which is not your primary residence, you may have a capital gains tax liability.
See the below links for further information and how to report and pay on property disposals:
Capital Gains Tax: what you pay it on, rates and allowance
Report and pay your Capital Gain Tax: If you sold a property in the UK on or after 6 April 2020
How do I report and pay Capital Gains Tax on property disposals? - YouTube