Fairly sure you can continue under RAAus if you just want to fly for fun. The other thing to consider is ADHD isn't specifically called out in the AustRoads standards so you may be able to hold a C2 Basic as the neurological questions are if they have a significant impact, yadda yadda - but bear in mind CAsA has, in their infinitive wisdom, added additional questions above and beyond the AustRoads standards
Finally, you may be able to obtain a Rec Aviation Medical Certificate, but again, you can't do endo's and the rest, it's strictly Day-VFR, <1500Kgs etc, but that's enough to fly for fun.