Do you know how much it costs to see a herp vet?
It was a few years ago when I took one of my axolotls to the Warranwood vet clinic. Luckily, I'm sorting out my overflowing papers to (finally) file away, and managed to find that vet receipt.
The consultation for an "exotic/unusual pet" was $81.80. But, bear in mind that this included the vet taking a gill sample from the axolotl and conducting other tests, as she (the axolotl) had a severe bacterial infection. So I imagine that your consultation will be more 'straightforward' and hopefully won't cost that much.
Whereabouts in Australia are you based? Other Australian members may be able to recommend a vet they've had success with in the past if they know whereabouts you are.
Does the leg look like it may come off by itself? If there is no sign of fungus or infection, you can wait a couple of days before taking the axolotl to the vet, to see if the leg drops off naturally.
Are you able to take some close up shots of the leg? The photos you've attached are rather small; it's hard to make out details.