Disability Living Allowance?

Hiya, my husband has degenerative disks in his back and bone damage to his knees, which often mean he can't walk or move at all. We filled in the forms for Disability Living Allowance (DLA) and we received a letter today, asking my Husband to attend an examination with their Doctor next month. As we have never done this before, I am wondering if anyone knows what to expect from this meeting, what questions they will ask etc. Are they very different to normal Doctors/Specialists in terms of what they want to know? Any information would be fantastic, thanks so much in advance xxx