If you can change the nappy without waking her then it would be fine to do that. Usually though people don't as they don't want to risk waking them.

WRT nappy, it depends so much on the child. When I used cloth, I used BBH Bamboo with wool covers for night - the wool seems to last longer at night than the PUL. With one DS I needed a booster and he still sometimes wet through. The other DS was fine all night with just the nappy and cover. If what you are doing isn't working, there are specialist night nappies. Or you could try an extra booster (if it will fit!) and a wool cover instead of the PUL.