Multiple Osteoarthritis - Work Capability Assessment.

Hi I am Graham Lister DOB 05.11.1958 and suffer with diagnosed Multiple Osteoarthritis in my Foot, Knees, Lumber Vertebra - causing sciatica, and Upper Ribs. I have been invited by the DWP to have a Work Capability Assessment on Friday 2nd JUly 2021 as my Doctor has deemed me unfit for work. Can you help me with any information or action plan I should follow to help me please.