worried about F2F Assment

Around January this year I had to take our son to his PIPS F2F I was myself My son told the into the room he told them that I did all his bills via bank and I am his appointee, and really have to look after his well being because of his mental health.
Now I am worried that I am going to see the same person, Just worried because I am transferring from DLA to PIPs I got the letter on Thursday last week for my medical on 7th June I was due to have surgery this Thursday. but got the call this afternoon they canceled it really don't know what Am going to do. I worried so much that I cant get across the pain I have.
My doctor is really not good last week he got cross with me because I asked him a question about my medication I been suffering with Gout and cut a long story short my chemist question the amount of pills I had with out a break when I asked him he very angry sat back in his chair and said "Well I am the doctor here you going to question me" I told to him it was my chemist not me anyway I got a screen shot from my visit from the nurse and he has put on it re gout Treatment refused.
I have the feeling he has not been very helpful for my case Just worried its not going to go well it says in the pips pack they don`t want letters from hospital do take them or not
Help please
Also do I say I volunteer for 3 hours once a week at a hospice shop do i tell them ( that helps my mental health) gives me something to look forward to a week

I have Fibromyalgia RA load of other stuff