In Victoria they have changed it to an opt in system which means that SRI is now "taught" in fewer schools. It is mainly done by ACCESS ministries which are an evangelical Christian group that gave a contract to do this with the government. They are not teachers, the curriculum is not assessed by the dept if education. It is up to the individual principal of the school to say if they will offer SRI or not at the school. Students who do not opt in when it is offered aren't allowed to do any other classes, generally they read or play games.

Especially as you are not religious I would encourage you to look into it further. FIRIS (fairness in religion in schools) is a useful organisation for information.