I've done my part. I joined the T&G. I am only one man. It's up to anyone else to join if they want to. Numbers are growing, but slowly. I rather suspect apathy will prevail and next time around we will be subjected to a similar scenario. If that happens we only have ourselves to blame.
I'm not convinced about Balpa, but I would join there as well if there were sufficient levels of membership.
As I've said before, I'd rather have everyone together, Flight deck, cabin crew, engineers, admin and office staff.
As far as dedicated forum, still waiting for a response from Pprune admin.