Because the school were not helpful in getting an EHCP for my son we took it upon ourselves to employ an advocate to do it on our behalf. She then told us about the access card application which she did and also some other things which I can’t remember. We met the lady at a local autism roadshow.
I'm sorry that you're finding it stressful. If it's any comfort or consolation, it's important - for good reasons - that they see enough evidence in support of each symbol that you've applied for. As they explain here:
"For the Access Card to be taken seriously by providers we have to make sure that we are making accurate decisions related to need and impairment and we only do this with enough information backing up the detail that you give in your form."
In addition to the information offered in the article that I linked in my previous reply, this one provides more information about their policies in respect of each symbol, along with some comments about the kinds of supporting evidence that can be useful - as well as some that aren't:
