3rd party insurance is nationwide, which ever state it is registered in, you are covered, but it has to be registered, you cannot buy just insurance

I'm not trying to be a smart arse but if [for example] you've shipped the bike from the U.K. to Oz, and you've got proof of U.K. insurance [i know that's pretty meaningless but bear with me], registration papers [that is proof you are the owner], vehicle roadworthiness certificate, road fund [tax] licence affixed on the bike, a carnet du passage [which negates the need to register the bike] and a full motorbike driving licence why you can't just buy TP insurance is beyond me. But free in NSW! If you arrive in NSW of course.