@LesleyA
Well, Australia was quite a surprise for us having had school around different continental Europe (not UK, not Ireland) countries and I will try to explain the main differences:
In UK, The National Curriculum is constructed in five Key Stages:
Key Stage 1 - Foundation year and Years 1 to 2 - for pupils aged between 5 and 7 years old
Key Stage 2 - Years 3 to 6 - for pupils aged between 8 and 11 years old
Key Stage 3 - Years 7 to 9 - for pupils aged between 12 and 14 years old,
Key Stage 4 - Years 10 to 11 - for pupils aged between 15 and 16 years old, and
Key Stage 5 - Years 12 to 13 - for pupils aged between 17 and 18 years old.
In addition to staging written here, and streaming which I mentioned further up, there are other peculiarities which are different from Continental Europe, from Scandinavia to Greece.
Private schools and religious schools are very common, and many of these are single-sex . There are fee-paying schools, some are very very costly,
Even State schools, which are free for all pupils, are sometimes run by the Church of England. In Australia, there are many State run high schools which are single sex which depending on your culture you might find very strange (I am French)
Schools have assemblies, during which pupils are gathered in the hall and a mix of information, rewards, or even prayer is done.
Schools have a compulsory uniform, even the state ones, and rules apply also to haircut (how long for boys) or hair style (long hair must be tied up). Pupils can be send home or given detention for uniform violations, even wrong socks.
School enrolment rules are very strict and you should check the schools in your area.