Hmmm...I don't know of road clubs adopting cyclocross in Sydney, however a few Mountain bike clubs have dirt crits/cyclocross races. http://www.mwmtb.com/content/ These guys are northside and have dirt crit series...you don't have to have a cyclocross bike to race, but it helps! Give them a call or send them an email, they're pretty relaxed (and joining an MTBA affiliated club is far less expensive than joining a CA Road club).