Thanks @nathank !
I will take another look.
A trick in my case is there are something like 15 qualifying user characteristics (currently identified via multi-select custom user field) for access to the private forum area. For better or worse, my first thought, for simplicity, was to try and control access levels via this one multi-select field somehow.
Sadly the Discourse Automation plugin at least does not seem to distinguish anything beyond a simple populated vs unpopulated state for the field in custom user fields (essentially a tick box) - I presume the same may apply for the Custom Wizard plugin?
** EDIT ** for some reason I can’t even seem to install this particular plugin Discourse Custom Wizard Plugin install failed - Support - Pavilion - will report back here once resolved
** EDIT ** now installed (a wrong path used in nano)