Could really use some urgent help

Hi,
i am new to the forum but could do with some advice. I have been off work for five months with depression stemming from stress at work due to what I consider to be victimisation at work by my boss. I am hoping to go back to work soon (my latest sick note expires this week and I am determined it should be my last) but have been telling work my issues with my boss for some months. I had a meeting with O.H. to discuss this a month ago and we decided that mediation was the way to go. Since then I have heard nothing, they phoned me this week to ask me to extend my sick note because they want me to see their doctor in order for him to assess my fitness to return to work. However, there is still no sign of the mediation meeting. I sent a letter last week asking but have had no reply nor heard anything. The O.H. dept asked me to "come back and see how I get on" but I think this is unacceptable as I will be gambling on my health. I am not sure of my rights here and am expected to go into work at the end of this week. They are (I suspect) hoping I will just come back to work and things will be ok. Any advice would be gratefully received. Thanks in advance.

You have right to consider your health first. on the other hand, with long time leave to your work it was considerable that they get their momentum of work without you..