Capital Gains Tax - Sale main home exemption. Post Brexit.
Very helpful member
It is crucial this property is located 'inside the European Union' and not outside for the exemption to be applicable.
https://balcellsgroup.com/capital-gains-tax/
'Take care when selling your UK home' if moving to Spain so not in same Tax year you become resident Jan 1st to the 31st Dec. (If not EU citizen) Consult an expert.