Excellent advice JoJo. Two things to add. I always get someone who knows the claimant to write a few pages on how they know the claimant and how they see how their disability effects them. Not a story, but just to the point. Any extra evidence is good evidence.
One other thing. I always pay to have the ‘Benefits and work guides you can trust’ website. It costs about £20 for the year. It’s always updated and covers a lot of the legal definitions and court rulings of those that have been through the tribunals. They have a lot of case studies that will define some of the jargon or questions that are designed to throw you. When I done the CAB training they used it. Good enough for them, good enough for me.