Advice on starting a PIP claim

Hello all.
I am currently looking into claiming PIP and looking for advice on what the best way to go about starting that might be for me. I was diagnosed with Autism Spectrum Condition (level 2) at the age of 37 last year.

I can speak on the phone if I really psych myself up and am well prepared with any information I might need as I would most likely just have to pay for it later with a tension headache and some time to decompress and analyse the encounter. Problems might occur if they catch me off guard with something unexpected though as I have that automatic tendency that a lot of autistic people have to give a quick one word answer to cover for the fact that I am still thinking- its the sort of thing that before I was in the ESA support group used to get me in over my head by saying yes to things before I understood what I had just agreed to. Is that likely in the initial PIP claim call or is it just a routine information harvesting exercise?

I know I could also try writing and asking for a form to fill in, but I have heard that this is both much slower and that they sometimes refuse to send it. Writing is better for me in that I have time to properly think about what I am saying, and I don't have to worry about asking someone to repeat themselves.

I had an ESA review in late 2019/early 2020 that resulted in me being moved from the WRAG where I had really tried to engage but kept making myself ill by not understanding my problems to the support group as I had by that time started the process of my autism diagnosis (its a loooong wait) and was much better able to express what my problems actually were, and much to my shock after a face to face just before the covid lockdown ended all that I quickly got a result that placed me in the support group and not a need to appeal as I always had before. Part of me is suspicious though that this was due more to covid than me being taken seriously. I had people telling me at places like the Citizens Advice when I got help with that review that I should look into claiming PIP but I was wary of any more contact with the DWP than I had to as due to the face that I often had to appeal all the way to tribunal just to get placed in the WRAG I found dealing with them rather traumatic. Now though the realities of living with my parents that are getting older and being entirely reliant on my 76 year old dad to drive me to any appointment I am becoming aware that I need to do something to help give me options and support when I can't be so reliant on my family for everything. Hopefully that is a long time off but reading about the time it takes to process these things makes me think I can't afford to wait until I am already in over my head.

Thanks, I have downloaded the guide and read the part about starting a claim. It does help to know that they won't be asking me to go in depth. It sounds pretty much like I can just prepare myself a list of info. I can probably handle that over the phone if I pick a day when I'm well rested and not pre-stressed. There would most likely be an issue if they ask something outside of that list but I'm guessing that's unlikely.

Shouldn't be a problem showing the duration, Autism is a developmental disorder that is lifelong. Technically it started sometime during my early development but even if they were to argue diagnosis is the start that's still last year. Despite what some quacks that get people to drink bleach might say there is no cure

I eventually managed to do the phone call and start the claim, and today the form arrived.

Is it acceptable to type my answers and affix them to the form as additional sheets and just write on the form "see additional sheets page..." for each question? I used this method about a year and a half ago for my ESA claim as I find it easier due to the ability to edit etc as it often takes several iterations to arrive at something I am satisfied with.