Steps to obtain (this was performed on a MacBook for reference):
1. Open the App Store app
2. Select your profile, Select account Settings, Change country to United Kingdom (if it fails here it is most likely as you have apple store credit, therefore you either need to remove it or try a different Apple ID)
3. Click on the link and obtain deal.
4. Revert back to Australia as the Country and it should work.
Note: no VPN is needed just change the Apple ID location.
Renews at $14.99 a month if not cancelled prior to expiry.
Let me know if it doesn't work and I'll remove the post, but I think it should.
Unfortunately you can't change your Country/Region without cancelling any existing subscriptions e.g. Apple Music