I need Help please, DLA/PIP UC ESA I

Hello, I've just joined, can anyone please help me understand, how i get help through this Forum? I've paid the fee & I'm not sure how everything helps.
I am disabled from birth, with left hemiparesis cerebral palsy, I worked until 30 years ago, when I lost my job through my walking, ruining my facet joints in my spine & am in receipt of ESA support group contributory, DLA high mobility middle care ,I have recently though had to claim for my wife on UC, who has now got mental health due to a situation created by her employer & then they dismissed her on ill health & stopped her getting her pension. I have a pip assessment on the 9th Sept.
I asked when they sent the pip form, if they could use my DLA paperwork & was told yes, I had help from Citizens advice fill in the pip form. I was then invited to a assessment miles from my home. I had this appt cancelled. I was then contacted by phone to arrange another appointment., I told the lady that I have a degenerative condition & she said you've sent no evidence with your form, I said you're using my DLA paperwork, she said no we have no access to it. Due to this I have had no time to see my Doctor to get a updated form, although I have managed to get a Dr appt on the 6th September, 3 days before assessment in my home town.
I told them that they had sent 3 years ago, saying I would have a home appt & that they never got in touch with me again until now, as due to my disability & being tall, I needed a higher seated chair with arms to help me get up & down & that due to sleeping problems could I please have a afternnon appt, as a reasonable adjustment under the EA 2010.
The lady told me , I will hold off appt, while you get report from GP & we could look at doing it by paperwork. I said thank you I will get the GP to write to you.
Well I received the pip appt for the 9th about 5 days later.
I rang assessment & said by not giving me the full facts about using DLA paperwork, you've put me in a position of not being able to get a GP report in before assessment, & I would like a reasonable adjustment for a suitable chair even if you can't change the time.
the answer was their should be a suitable chair it's a doctors surgery you're going to?
I rang the DWP & a really nice guy, went & asked what should happen with long term DLA moving to pip, & he was told that long term DLA can be used as evidence. He suggested that if I was not happy I should complain to assessment.
I rang back assessment & said, you can use it DWP says you can. I got the old GDPR from the Manager, I said I've given you permission so no problem. I then get well we need up to date information, some people have got beter, I asked what part of degenerative do you not understand? I told her I was putting in an official complaint, as far as I'm concerned they are breaching my human rights & the EA 2010 , as I was asking for reasonable adjustments.
I'm stuck & don't know what to do??
Our property is on the market, as my wife now has a disability created by her employer, hopefully it will sell before, i have no money coming in & the bank swoops in.
I've rang to try & get free prescriptions, they have told me I can't have them, unless I can get UC.
The train lines feel like an option, but what would happen to my family, plus I worked on the tubes in London & saw what happened to drivers mental health after a suicide.
I was on suicide watch 6 years ago, my wife is now on £58 per week pip, after slogging herself to death in a busy A&E for 14 years.
Please someone help direct me on this forum, I'm lost & just need a leg up.

Thank you kindly for your response & I will follow your advice about the appointment.
i will read through the links you have given, I just wish that I didn't have this disability at all, I've tried so hard to get medical help to get back into work, all to no avail.
I would rather be grafting at work, than in this position.
I will update what happens after the 9th September.

Thank you for your advice I will follow it, & see what my doctor can do in the 3 days.
I don't mind being assessed, but I've had so much contradictory advice from the assessors, & then the DWP telling me the opposite, I could have seen my GP at the outset I told them & they could have had as much info they required. I stupidly thought by signing the form, that they could get in touch with my GP would be ok, but they then told me, that Gp's are worried about GDPR, so they wouldn't ask without me giving the GP a letter.???
All I can say is common sense went years ago, why did they just not say in the first instance could you get a up to date report from your GP please?
I'm sorry for the rant, maybe you can see how my experience with these people has been with me before i even go, I could get more sense out of a toilet door.