Welcome swallow

You can discount Barn Swallow as that does not have red extending onto the breast, it stops at a dark band on the throat. Not visible in this picture but it also has very long tail streamers unless it is a first year or has just moulted.. You can also discount Pacific Swallow as that is not normally found anywhere in Australia. A few very rare vagrants have been recorded in the extreme north of Queensland but that is all. Welcome it is!

I think it's Hirundo neoxena. https://commons.wikimedia.org/wiki/File:Hirundo_neoxena_PM.jpg

Looks like a swallow to me.