Try the Internet
The Internet is going to be one of your best resources for finding BBW singles to date in Australia.
1.You will be able to find general sites that are targeted to Australians, or adult sites that offer a more open minded atmosphere. Browse the site before you sign up, and search within your area to see how many BBW singles are signed up. If you like what you see, you can go ahead and create your profile. If not, then keep looking until you find a site that has a good variety of members.
2. Here are some BBW Dating Site dedicated to BBW Singles in Australia, such as BBWDatingAustralia.com. You can find what you want in those dating sites.
PounceBBWNight: Australia's FIRST and ONLY #BBW Club Night, held monthly at @wholelottaloveb in #Melbourne!
BBW Sydney: http://www.meetup.com/BBWSydney/