People need first aiders. Life happens, accidents happen. Mental Health first aiders do pretty much what your physical first aider does. They help identify something is wrong, they offer a bit of help or support but more importantly, they get the person to the right support for what's going on.
These can vary from a half day Awareness course to full two day Leading FA4MH course. The longer the course the more conditions, signs and symptoms are explored, plus there are varying levels of support. The training a manager has, might be slightly different to what a peer would have. There are reasons for this which would be covered during consultation. Course information here
Mental Health first aiders are a great asset. They can not only help and signpost what support is available, they can drive awareness days or encourage colleagues to get involved in such things as charity events.
Maybe you opened a new location, had changes in personnel or just implemented new ideas? Does your wellbeing strategy need updating. I can help you with this.