off sick from work for 3 months

don't know if this is the page to post this. but some advice would be helpful.
i had an accident at work in feb this year, i have been off sick since.

there was a problem with the hand brake on my work van, you would pull the hand brake up, then move your foot of the brake pedal, as you were exciting the van it would start moving, you then had to pull the hand brake up another 3 or so clicks.i verbally told my supervisor and the fleet manager on numerous occasions. the fleet manager just told me it was a 2 stage hand brake and that it was meant to be like that.
on 13th feb i did the handbrake and got out, my work partner then shouted to me that the van was rolling, so i jumped sideways through the door to pull the hand brake up, and hit my ribs on the seat controls , this caused a lot of pain and sleepless nights ever since.
i had a letter from my firm to attend a video conference on Tuesday ref the incident, citing concerns and that i might be subject to disciplinary measures from it. the conference consisted of me my union rep, and HR , my manager and my supervisor. should there have been someone from health and safety there as well. I got the feeling from the meeting that they are trying to get rid of me.
i then had a occupational health person ring me on Wednesday.on the meeting they wanted to know why i didn't report the accident on the day,i did see my supervisor the next morning and informed him of it, i asked for it to be put in the accident book, be he refused and just told me to near miss it, he is going to say he cant remember or what ever.
clearly my next move is to put a accident claim against them isn't it.