I would not worry at all about not speaking Greek. Most Greeks speak English at a very high proficiency. It's a tourist nation, English is the language of tourists. Also, media here is consumed in the native language with subtitles.
"Education First’s 2023 English Proficiency Index (EPI) ranks 113 countries by their English skills. Greece, with an impressive score of 602, ranks 12th globally and 10th in Europe, highlighting its robust “English as a Second Language’ proficiency and comprehensive approach to language education." [0]
"Education First’s 2023 English Proficiency Index (EPI) ranks 113 countries by their English skills. Greece, with an impressive score of 602, ranks 12th globally and 10th in Europe, highlighting its robust “English as a Second Language’ proficiency and comprehensive approach to language education." [0]
[0] https://www.tovima.com/society/greeces-impressive-english-pr...