Check with your relevant consulate for visa requirements for travel to Greece from your country. Greece is in the Schengen zone so you may require a valid Schengen visa. British passport holders don't need a visa but as you will be entering Europe, make sure you haven't exceeded the 90 in 180 day limit for time spent in Europe. If you are a foreign resident living in Turkey, you will need to show your residency card, as well as your passport, at Turkish passport control on exit and entry.