For more information on becoming a doula, go to www.dona.org
. I've been a doula for the last 9 years and it's been very rewarding. I work as a volunteer doula as well as free-lance, and the experience has been wonderful.
DONA is not the only certifying organization, but this is the one I'm most familiar with.
FWIW, I'd be looking for another doctor also. A doctor provides the medical services, but does not provide emotional and physical support during the entire labor. I would ask him why he doesn't allow doulas, and as a tongue in cheek question, I'd ask him if he's willing to perform the tasks of doula (supporting you while vomiting, changing positions, massage, general encouragement). If the answer is not acceptable or has an "off" view of doulas, it sort of shows two things:
1. Lack of knowledge of what a doula does.
2. Bad experience with a doula. In this case you have to demonstrate that not all doulas are like this (depending on what happened).
It's very telling if a doctor doesn't want a doula present. It says to me that the doctor does not want to be challenged in the smallest decisions, and is afraid of someone who helps the parents make decisions for themselves.
This is just my opinion on the matter.