Australian Constitution - Section 116 - Commonwealth not to legislate in respect of religion
The Commonwealth shall not make any law for establishing any religion, or for imposing any religious observance, or for prohibiting the free exercise of any religion, and no religious test shall be required as a qualification for any office or public trust under the Commonwealth.
This is definitely not as strong as USA's state and church separation. But there are grounds to work with. There is an ongoing high court challenge for a federally funded state program across Queensland where federally funded school chaplains may conduct Christian prayers on all-school assembly; at significant school ceremonies; hold lunchtime prayer/Bible study sessions and engage with students in the classroom, playground, school excursions, school camps and sport. Chaplains oversee and conduct Religious Instruction classes and on-campus church-designed and run programs including Hillsong 'Shine' which connect children with evangelistic off-campus clubs, programs and camps.
Donation towards this high court challenge is available at http://www.highcourtchallenge.com/