Why not contact the Queensland Dept of Education for up to date information? In Australia she would probably have to go into Year 11 ...remembering that the academic year starts in late January of course. Wider age range in each academic year in Oz also as there is more flexibility on when you can start according to birthday... There is no Year 13 in Qld as far as I am aware so year 11 and 12 are the two-years in which you study for leaving school!
This is a hypothetical question....or almost hypothetical. We have Australian passports, so it is not entirely beyond the realms etc etc. If DD were to move to a Qld school while she is in year 11 in England, where would they put her? Does anyone know please?