I really hope all goes as you'd like. My first labour was 23hrs and second was 3.5hrs but that involved the synto so not sure how things would have gone otherwise. I know with gas it also made me feel a little yuk at timse and what they'd do is turn that off and i'd just have air, breathing and biting down on the mouth piece seemed to help me through contractions aswell.

Good luck can't wait to hear how you went