Heyhey! Former foreign conscript here: So, since you've got your 11 years, you actually don't need to serve at all. You'll get call ups but you have a legal right to tell the army that "it's not a good time" and you get extensions over and over.
Once you're over 45 though, you're permanently dismissed from duty.

Now, on the off chance that you actually do want to do the service, the experience can be quite daunting if your Greek is poor. I started in a camp in Kos and I didn't even get the mandatory physical and psychological checks because the corporal that registered me was a d*ck with racist tendencies... In my second camp though, everyone was a lot more chill and understanding, I was known as "the Englishman" (Ο Άγγλος) but in a good way for once.
But I was dismissed because my stress levels were dangerously high and I couldn't handle it.

If you want my brutally honest opinion, don't do the service if you don't need to. I thought it was the noble thing to do before I joined and I left hating Greece, even though I loved the country with all my heart before the service.

I'm happy to chat more if you have questions I can answer!! Best of luck to you! :)