Hello Simon.
If you plan to stay in Greece for some years then you will eventually understand some common phrases,just be patient and this will come.Now,about how to learn Greek,the truth is that Greek is a difficult language,at least this is what i read from articles written by western people.As you can understand Greek language is a lot more difficult because is a whole language family by its own(i mean its not included in the Latin or Anglo-Saxon family of languages and more).
The good thing is that because you are from Turkey you should know that we have some words not exactly in common but really close.So first things first for you,learn how to pronounce the alphabet,if you do that then you will be able to read most Greek words and that alone is very very important,since in Greek language its the concept: "What i see i read",meaning that most of the times you dont need to pronounce some words with different accent or way to be correct.Other than that,if you are able to find any resources online for Greek languages i would suggest you to think practical,what do i mean here.First learn the communication phrases and after that how to differ the way you speak about a male,a female,or a neutral after this i suppose you should put the weight of your effortes to understand better the way the verbs are used because its very important.
I know that my guide here must not be that "professional" but i feel that if you take this way i just described you,you would be able to become an everyday speaker easier.I hope i helped
Good luck everything you do,George.
