It is legal -in New South Wales- to drive an unregistered vehicle to an ‘approved’ location for the purpose of obtaining registration (for a safety inspection, to get a green slip, RTA, etc), providing you travel via the most direct route with no unrelated detours along the way.

More info on the RTA website here:

I have been pulled up riding unregistered motorbikes (to obtain registration) a few times. While I’ve never been charged, it’s still inconvenient when you’re late for an appointment with an inspection station (for example), and with a ‘strange’ or ‘suspicious’ looking bike the police officer(s) might want to spend some time sussing everything out.

But, there is an easy way to avoid police hassles :-D
This most recent time, I wrote a “Letter of Intent” and put it in my pocket (along with previous rego papers, greenslip for unregistered vehicle, etc). The letter stated along the lines of “I ___ ___ intend to drive vehicle displaying registration plate ___ to _____ located at ____ for the purpose of obtaining a safety inspection blue slip.” etc, etc.

When I was pulled up, the officer took one look at the letter and sent me on my way with a smile.