G’day Jason ?
Sorry for the very late reply as I’ve been busy with moving forward with life!
I’m aware of two ranges in the Newcastle/Hunter region that one should be able to access in a chair and accommodate. Cessnock pistol club is very well set up and access is pretty good with ramps. The only down side is getting from the car park which is all dirt so wet days would be a bit tricky.
Seaham range is the other and like cessnock pistol the car park is dirt unless changed as its been a while since being to both.
Only prerequisites is for gun license, the mandatory knowledge test and NO criminal record for 10 years or longer. All info can be found here https://www.police.nsw.gov.au/online_services/firearms
Hope this helps.