UK citizens can travel to Greece and stay for up to 90 days within a 180-day period for tourism, business, or family visits without needing a visa. Please check the UK Government's latest advice: https://www.gov.uk/foreign-travel-advice/greece/entry-requirements

If you're travelling from the UK, you require to have a passport that is valid for at least 3 months after the day you plan to depart. Check the document's ‘Expiry Date' for clarification.