They will just want to talk to you about how you mh issues affect you and how that impacts on your work. Then they will try and work out if there are things that you/your employer can do that will help to minimise the impact of your mh issues on your work.
I have found them to be supportive, and they genuinely had my best interests at heart. They listened to me when I wanted to try and stay at work, and after I ended up having 6weeks off they supported me to do a phased return. I wouldnt have been able to keep my job without support from occ health.
I hope it goes well