I had a doula with DD2, she was fantastic and even though she felt she didn't do anything, she did loads:-
-taught DH counter pressure to relieve the slight back pain I had.
-seemed to intuitively know when time between contractions was increasing so would recommend I get off the ball or change position in some way. I know now she was obviously timing my contractions so she would know when the next was expected but she did it in such a way I never felt her focus was off me.
-help DH be there for me not for dealing with timing contractions/letting MWs in etc.
-was really reassuring when hospital had told DH there was no MWs to send to homebirth. He knew with her with us I could last a bit longer until shift change. DH phoned at 5am-ish, doula arrived at 6am, shift change was at 7.30am. MWs arrived about 9am DD2 born at 10.35am
-told me that it was the baby I heard crying wheb I kept asking what the noise was I was still waiting for it to get really painful and expected pushing to last longer than it did (4 mins!!!!!!)
I'm expecting again and have booked her for this home birth too. I can't wait to do it again.
Good luck with your pg and hope you find a really good doula to help with your labour. Try reading 'Blooming Birth' it has some great advice in it about labouring with a doula.
N.B. Obviously we knew our Doula was not a medical professional so could not legally deliver the baby (and we hoped this would never come up) but we discussed with the Doula what would happen if the hospital refused to send out a mw, she would go into another room and DH would 'catch'. The part about being able to wait til shift change was to do with coping not catching!