Not bad for a beginner!
I can't remember seeing a better image of the Pavo Spiral anywhere. It's one of my favorite supernova search regulars. I wonder if your autoguider is chasing the seeing a bit? Atmospheric turbulence over Perth is certainly one of the limiting factors, more so than thermal considerations.
I assume there's not much you can do about the smeared diffraction spikes?
Cheers, and please keep them coming!
Andrew.