Thank you for your reply kjodle.
I have thought about using subdomains for the various regional sections and if cpanel allows use deny IP to manage access. Though i’m not sure if cpanel supports denying access to individual subdomains.
It seems a bit resource intensive having separate WP installations and content for each but outside of some clever code it probably is the only way of achieving the task.
The offsite access was something I had thought about but couldn’t come up with a solution outside of the membership option you described (thins may be an option for future development though).
If I do come up with a working solution I will update the thread in case anyone else has similar thoughts!