If you can't do the birth center for some reason, instead of a doula you could consider a MW practice that delivers at a hospital. I have that for this time and have been told if my previa doesn't clear and I need a c/s the MW will be with me for the whole procedure as support, even though she obviously won't be doing the surgery. It's wonderful knowing that if things can't go as I'd like I'll at least still have an experienced medical provider in favor of natural birth on my side.
I hope everything goes wonderfully for you, though. :)