Good luck Whiff, I've been through 3 tribunals over the years and granted each time. I won't lie, it is scary, but if you tell the truth the panels are very good. I was granted a 10 year award with a suggestion I not be checked again, we shall see.
Mine even suggested that my 'accessor' be fired - he was an ex paramedic with ideas of greatness - tweed suit and a fob watch with Albert chain! The DWP staff member apologised too.
Sadly, I go through it each time as they've never heard of my condition, Oesophageal Spasm, with daily attacks and reliant on options.
You seem to have had wonderful advice and back up, and I hope someone can go with you as the mental support really helps xx Deep breaths, and know you'll be OK. Also, after you win, you may receive a letter stating that the DWP are considering an appeal - don't panic, they never do. Take care Whiff x