I am on PIP for severe agoraphobia and anxiety. I won't lie, it's difficult to do and I've had to appeal to the tribunal 3 times after being turned down after assessment and mandatory reconsideration. This time, I was granted higher level mobility following the mandatory reconsideration.
I had to get proof from a medical professional to get a home visit, but these have all been granted with almost no fuss.
A couple of times I have requested help from my MP and he has been helpful. I include a printout of the email in the stuff I send to PIP. The last one included a very frustrated story of what it is like living with an invisible mental health condition that people don't seem to understand, that there is a lot of talk of helping those with MH conditions, but when push comes to shove, if they can't see it, I haven't got it.
It helps to put down things like 'I am unable to walk my children to school except for 2 days a month when my friend can come with me'(change to suit you!!) because if you say 'I can take the kids to school twice a month but no more' they just hear the 'I can' bit.
I included a list of all the feelings/thoughts etc that I experience when I leave my home (and frequently when I'm in) I made sure to explain that what I experienced was not just 'a little bit nervous' but actual 'I have cried in the street because I am 20 steps from my home and feel like I'm actually going to die, not just saying it, but genuinely feeling that I am going to die'. I also got a doctors letter, although, as lovely and helpful she is, the letter wasn't great.
I made an incredibly depressing list of things I am unable to do like take my children to the park, or shops, can't go to school plays, have missed countless weddings and family gatherings etc.
I finished by saying that I realise that all these things sound stupid to someone who has never experienced anxiety on such a level, but don't dismiss the extent of how much it impacts on my life.
Wow!! Sorry, that was really long!!! Hope some of this helps. What I will say is, expect to be turned down and to have to do at least a mandatory reconsideration. they seem to turn most people down at first to see if they can get rid of them!! Same with the MR-horrible to say it, but that's how it seems to work. And it takes a looooonnnggg time. Weeks to get the form, weeks for it to be looked at, months to get an assessment etc etc.
I'm not saying this to scare you off of doing it, just think it's best to be prepared.
Fingers crossed for you, and don't give up!!