Worried about not getting evidence from my GP

I would very much appreciate some advice. I am currently on DLA because I suffer from severe clinical depression and anxiety. I recently filled in my PIP form and waited to hear what would happen. I was sure that if there was a face to face assessment, they would hold it at an assessment centre, which would be difficult forme to get to because of my anxiety levels, and I expected to have to struggle to persuade them to do a home visit. However, to my surprise, when they replied, they did say I needed an assessment but said it would be at my home.

It is in just a week's time, but now I am wondering if I should have got a letter from my GP (the only health care professional involved in my treatment). The thing is, I don't see what he could write. Years ago (2005), a GP where I used to live put me on a strong antidepressant, saying that this was the most effective thing they could use and if it wasn't enough, there was nothing more they could do in terms of drugs. When I moved to a new area, the new GP agreed that this was the most appropriate medication, and just kept on prescribing it. The only change he made was to increase the dose to the maximum permitted when my condition worsened. So that is how things have been since around 2005 when I was first prescribed this drug. I was sent to a psychiatric team for assessment in (I think) 2015 after suffering the traumatic effects of an assault, but that was just one visit.

I very seldom see my GP, because when it comes to my mental problems, there is really nothing more he can do. Plus, it is an ordeal for me to go there, because of my anxiety.

So with all this in mind, do you think it would help if I contacted my GP's surgery and get them to rush out a letter?

I do have two letters from my GP to my housing association which describe my mental condition, but they date from 2014 and 2015. I also have a copy of the four-page assessment by that psychiatric team I visited. I could show these to the assessor when they visit me. Would that help? Thanks.

Thanks for that advice. There is a problem - my assessment is on September 1st but the earliest I can get to see my GP is the 6th. Would it still be worthwhile going, or would it be too late?