So, about education here.
The curriculum is set nationally for normal schools. There are a very few doing IB, Montessori. Home schooling is a thing here and mostly regulated in that they get inspected each year but there is a lot of free range in that. Each state then runs their own education department. www.education.wa.edu.au/ I will talk about the high schooling here.
There are three sectors
a) public (state schools). They have to take everyone who lives within their catchment. They are arranged so that each one has a specialty or two (ie dance, soccer, music, selective academic) and are loosely arranged in clusters for each geographical area. If you live out of direct catchment, you need to apply and qualify. State schools have a small, voluntary charge.
b) Catholic. These receive a moderate amount of government subsidy and the rest is fees. (These are what I know about so do ask if you would like more information. Prendiville College mentioned by a PP is a catholic school). A few are single sex.
c) Other denominations. This includes Anglican, Baptist and nondenominational Christian. They receive a smaller government subsidy and the rest is fees.
All schools can be inspected on www.acara.edu.au/reporting/my-school-website
The school year is the calendar year. Moving here over Christmas will be easier to slot in for the higher years (yrs 11 and 12). We only have exams in the final year, being the end of a two year course and that's what your tertiary entry comes from. All schools these days run Vocational Education and Training courses for those not looking to go straight to uni.
You are welcome to ask more questions. If you have any idea of where you might live, more information can be given.