DLA appeal for 12yr old son

Im absolutley terrified I'm going too mess up the appeal/tribunal for my son it's on the 16th Feb and the diasbility agency who helped me fill appeal paperwork in are not replying to my phonecalls's and I was hoping somebody could come with me as a rep but don't think that will be happening anytime soon either so basically need too find as much info myself .

I sent my son's DLA form off in March 2017 he had diagnosis of dyspraxia = motor cordination and forgetfullness ,I have to wash him,help him do buttons,zip's ect brush teeth ,get undressed ,ulcerative colitis = uncrontolled bowel movement's leading too soil night/day plus can be very poorly and was out of school due too sevre anxiety _sleep issues,anxiety attack's and colitis flares at the time, since then he has been diagnsoed ASD (know it's not diagnosis dependant but just too give idea on concerns /difficulties) he's moved too an SEN ASD school, has an EHCP ,few more condition's picked up,physio 3 times daily,camh's input ...now i've sent all these report's in but will they take any of this onboard ? I tried too write with help of CAB my concern's and his difficulties in the DLA form's but fear ive not worded them right ,he was born with Autism so had it when I put form in altough wasn't diagnosed till later on in year
my boy doesn't leave house alone due too a mix of anxiety and motor cordination difficulties ,I tak him school drop him at door and teacher wait's with him on play group tillI collect due too he just walk's in front of car's and fall's regulary and does not see the danger of moving vechiles,form tutor has agreed too write something too support us at appeal but is not sure how to word it as never come across this in a SEN school before

any advice or reading material gladly recieved as I'm so scared I will just go blank in the room but if I feel more confident I might not be as nervous