My transfer to PIP!

Hello everyone,
I hope someone can place a full stop at the end of some of my thoughts, as at present all I have in my head are question marks!
I have been claiming Dla for 18 years, ( I am also in the support group for Esa).
I suffer from chronic depression and anxiety ptsd following the traumatic death of my son as he was born at full term, the day he was due some 26 years ago. Since my Dla claim last time, I have now been diagnosed with osteoarthritis in the pelvis and lower spine, a wedge fracture and now fibromyalgia syndrome, which has progressed quite a lot of late in the chronic pain stakes! I am worried that now I need to change over, I have only ever been given the low mobility part of Dla due to the fact I don’t go out anywhere alone,and my mental health issues, but now I also have mobility and personal care issues on top, but never actually advised Dla for extra benefit before.
I am told I need to telephone to say I want to claim for PIP, and after reading notes on here,I need to say I want them to take my Dla notes into account, but this will not cover all my issues now? Will this be a detriment?
Even writing this I feel so anxious, to have to actually ring & speak to someone makes me feel nauseous.
Could anyone advise how long once you have rung to tell them you want to claim you get the forms etc, and how long before your assessment, as my dear husband is hoping, probably beyond hope in trying to take us on holiday at the end of May, as his life needs to have some normality! But I’m sure they will also hold this against me, even though I have to have wheelchair assistance, travel on a scheduled airline as crowds for charter flights make me panic as I have social phobias, and we only go to a place where we have friends! I am wondering if it’s worth it, but I suppose this is what they (Dwp) want us to do?

Thanks Gordon, does everyone have to have a face to face assessment for PIP do you know, I was put in the support group without as I fulfilled the exceptional circumstances ? I’ve read and frightened myself with lots of horror stories of the assessors just turning up, or lying & making things up, my home is my only place I feel anything like safe, so for them to come would be a nightmare, but going out into town is equally terrifying.