There are no specific expat communities in Greece that I am aware of although I would imagine there are many expats on the touristy islands such as Mykonos, Santorini, and Crete to name a few
You can retain more than a few words if you don't tell yourself you can't do it. There are plenty of things that are said often enough that you don't even have to try to remember them. You just have to be willing to listen..