RAAF experience
I did my RAAF pilots course in the late seventies. One candidate on the course suffered motion sickness at Point Cook. They tried to "de-sensitize" him by putting him in a revolving chair until he threw up everyday for 2 weeks. After that he went out on a training op and threw up again. He was gone the next day.
Maybe things have changed. Maybe you won't be so affected when you get to training. Just give it your best shot when you get the opportunity. Have a back up plan though. Not so easy to get a pilot slot in the RAAF. Even harder to get a fighter slot. However, its worth every effort. Good Luck.