To get into Nursing, you really dont need any individual subject as a pre requisite. Obviously you need to pass English, but that goes for any course with uni. Basically she is best to pick any TER subject that is going to give her the best result. I did english, maths and human biology and scored well with these subjects.

To be a registered nurse/registered midwife she does need to go to uni, to be an enrolled nurse she can go to TAFE. However you cant be a midwife as an enrolled nurse.
I believe some states were bringing in a registered midwife course so you didnt have to do the full nursing degree first. In WA you do 3 years bachelor of nursing and then 1 year post grad work, followed by 12 months post grad to complete the mid wife course (if you get accepted of course)

Personally, eventhough she thinks she wants to be a midwife, I would encourage her to do her full nursing degree and then qualify as a midwife. It just means that she has more flexibility with career choices down the track. I always wanted to do midwifery, but started nursing and fell in love with geriatric nursing and have now done it for 12 years.