Welcome to Communities, Ayesha
Have you looked through such as this:
www.mind.org.uk/.../

(It's absolutely great and most commendable to have an interest in this and to strive to work with it all, but many would regard promoting mental health in the workplace as not one of the principal aspects of professional HR Management, so you may need to be careful to keep your hand in too as regards these.)

Hi, I work in HR in the construction Industry. You might get some leads here www.matesinmind.org and perhaps ask advice on becoming a trainer. Good luck.

Welcome, Ayesha. Maybe consider trying to get to Manchester next month and talking to some of the exhibitors at the Annual Conference? I'm not sure where you're based.

There are usually quite a few exhibitors in this area.