You need to find out exactly what the laws in Australia allow, and what protections there are for you. (here, right now, you have to be considered dangerous to yourself or someone else to be involuntarily hospitalized, and even this is limited----and it is not easy to enter into a hospital voluntarily (lacking resources/beds/etc)---
You can access relevant laws, rules & regulations on line. If you need help navigating, go to a public library & talk to the reference librarian. (if one library isn't helpful, try another)