Natalie, imho the reason that trying to change the baby's position from 37 weeks on is useless, is because that is too late to begin...I think that if it can be influenced, it's by attention to excellent posture through at least the 2nd half of pregnancy.
My 2nd baby delivered OP. I was cared for by a private midwife at a freestanding birth centre. It was an excellent birth and my first VBAC. When I arrived I was 7 cm dilated, and I asked the midwife what the baby's position meant for the labour. She was very calm and said that it would probably take a bit longer than otherwise, but that mothers generally didn't find it more uncomfortable or difficult. Her calm assurance that all would be well was the best thing for me. Obviously I had no epidural...I didn't have any epi or tear either, the birth was completely unassisted.
LOL, I think the POP had a lot to do with my son's personality. It is exactly like him to want to struggle obstinately in an uncomfortable way, and then pop out gloriously at the end!!