my name is Kai. I'm from Taiwan and I'm a native Mandarine speaker. I taught Mandarine in Sydney before for 3 months and because of my study, I stopped teaching for a while. I had taught English in a private school in Taiwan for 4 months before, at that time basically my students were under 12.
It's not very hard to learn Mandarin unless you want to learn how to write. Speaking is the easiest part of Mandarin and there are plenty of movies that you can watch and youtube channels you can learn Mandarin as well! I can provide some of the resources. :)
In my opinion, it's super easy. Mandarin speakers are everywhere in Sydney, especially in Sydney City or Chatswood.
Talk to people and make some friends with Mandarin speakers.
If the current tutor is not available, check the availability of other tutors