Hi there! When are you actually due??? That might make you think twice about some clinics/midwives depending on the weather and road conditions.
In Germany you don't have to go to an OBGYN if you don't want to or need to. You can get all your prenatal care from a midwife. Of course, if you want ultrasound then you need to go to a gynecologist for this. So find a midwife (Hebamme) because she's the one who will be accompanying you during your birth, not a doctor. Of course, if you just show up at the maternity ward of a clinic, you'll be cared for by their midwives, but its nice to have your own who knows you inside out (no pun intended, heh). But ask if she's allowed to do births in the clinic you've chosen. If you're considering a home birth, then you're sort of in luck. It's legal here in Germany, but the number of midwives who actually do homebirths is sinking due to insurance reasons. And most of your midwives also do accupuncture these days, but ask, of course.
So here's a list of midwives in your area, some of whom apparently also speak English:
Here's another link with a whole bunch of resources. Apparently there's a Geburtshaus in Garmisch, too, where you can just go in, have your baby and head home. The midwives in all cases visit you for up to 8 weeks after birth to make sure you heal well, your baby is nursing well, etc.
Run this list by your dh. He'll be able to help you more. But do make sure to go to a "Geburtsvorbereitungskurs" - birthing class, find where you want to do "Rückbildungsgymnastik" (postnatal exercise class) or ask your midwife for a recommendation
For mother clubs, well, you can look for Krabbelgruppe, but you might want to look for other Englisch speaking moms and just meet them, especially if you aren't going to be there long and dont know the language. Maybe someone else can help you out with that. Are you staying on a base? If so, you might want to check with the base if there are any such groups there.
Good luck, mama!