Haha that's where I work now. Sue's going on a hiring rampage before uni starts and all the experienced people go back to school. She's a good boss, and the vast majority of us Boosties are lovely people =).
But I'll need to find a new job before i turn 19 because i'll be more expensive to pay, plus it'll be winter and half the rostered shifts will get cancelled because it's just so quiet. Plus the store isn't open on saturdays when it's cold. Sue is pretty ruthless with shift cutting, sending people home early in slow times etc.
Heaps of people get trial shifts, work for a few weeks and quit. Doesn't bother me, new people are slow. Keep at it, it's good spending money and you'll pick it all up pretty quickly.
Anyway, good luck. I'm sure you'll get a trial, everyone does.