In my experience (a couple of years ago), we contacted the legal dept for advice etc. on a dispute with our management over pay and conditions.
The advice given by ALAE proved to be wrong in several areas, it took a VERY long time to get replies to letters (if at all) and phone calls were not returned. Not what you need in an urgent matter.
I'm still a member but beware if you are only going to join to get legal help etc.