PIP Supporting Evidence

I am a carer for my son with an autistic spectrum condition and support a friend with severe depression,anxiety and trauma who will soon be transferred from DLA to PIP. The friend has now had the initial PIP phone call.I have 2 queries concerning supporting evidence:
1. Is it worth making access requests for all health and social care records where the friends depression and trauma is rooted in abuse of all forms during childhood and abusive relationships in later years including beatings, rape and other abuse. Although this evidence relates to years ago I feel it places the severity and continuity of her current conditions and difficulties in context.
2. Is it likely to prove detrimental, for both of them, that they have only intermittently accessed healthcare services in recent years. In the first instance there have been cuts in the availability and range of services locally. But centrally, due to there conditions its hard to make appointments or get them to attend when they are in a bad way. Secondly, if escorted to appointments,due to their conditions they find it really hard to cope with the travel, people or situation and cant face a follow up appt. Also both have mentioned that over the years they have tried the whole spectrum of professionals and interventions whereby they are just being told what they already know, in terms of therapy and strategies from previous therapy, which they have put into place and to some degree help them manage at a basic level,but also these strategies fail. My concern is that there is limited medical evidence,outside of their GP's, to provide as supporting evidence for recent years and the importance of medical evidence is highlighted in th Guides i've noted.