International Travel and attending Mass

Hi! I am traveling with a school tour group to Greece. I am forced to stay with the group. I’m trying to make it to mass and I’m hoping we will be somewhere close to the Holy Catholic Cathedral of Saint Denis the Areopagite in Athens.

On the website it says, “SUNDAYS & MAJOR HOLIDAYS:
07:30 & 09:30 - GREEK
11:00 - LATIN (with readings in Greek)
18:30 - ENGLISH
DAILY:
07:30 & 18:30 - GREEK
SATURDAY 07:30 - GREEK
18:30 - ENGLISH (First Sunday Liturgy)”

I think I will only be able to make it to Saturday vigil. My teacher said we will only be able to POSSIBLY have freedom at night. Does this mean the 18:30 mass will only happen the first Sunday liturgy? Or will they still have that mass time but in Greek? And by first Sunday liturgy does it mean the first Sunday of the month?

Either way I plan on speaking with my Priest in case I cannot make it to mass that Sunday.

Any help would be greatly appreciated.
Thanks! :)