SPAIN: REGISTER YOUR RESIDENCY
How UK nationals who plan to live in Spain for more than 3 months must register as a resident and on the padrón at their town hall
All the information in the next link:
https://www.gov.uk/guidance/residency-requirements-in-spain?utm_source=16d40792-4e52-4a91-9830-b3758d25b55b&utm_medium=email&utm_campaign=govuk-notifications&utm_content=immediate