Hello, and welcome to the HUBB.
I'm pretty sure you can buy European green card insurance at the border when you enter Greece. Greece is part of the EC, so, whatever insurance you buy in Greece will be good in the other EC countries as well.
I've only ever bought insurance going in the other direction (Greece into Turkey), this because I already had an EC green card for my return. But, considering that Turkish insurance is no good in Greece, I think it is pretty safe to assume that there will be an insurance kiosk for cars entering Greece from Turkey.
If you have some time between now and your planned entry to Greece, you might want to browse the "Where to get the cheap green card insurance" thread in this forum. Go directly to the last page, no point in reading all the posts from 10 years ago. There are several vendors mentioned there, you could order the insurance ahead of time, it will be posted to you by registered mail or sent by courier, and you would have the document before you even left home in Turkey.
Have a good trip... and be prepared for the exorbitant VAT in Greece. As you are probably already aware, the only people who pay tax in Greece are the tourists, and they have to support the entire country.
|