My best advice,as this is one of my professional areas of legal expertise, is take notes of all that happens. Remember that the assessor will watch every movement that your husband makes to assess it against the stated difficulties, so if a task is painful he must say so.
Don’t underplay anything, its not helpful to play the stoic and doesn’t give an accurate picture.
Lots of people are too embarrassed to be honest especially when it comes to personal bodily functions, don’t be!but be very detailed and honest about all the help he needs. try to make sure that you do not over estimate walking distances or under estimate the time it takes to do a task remember the benefit is awarded due to the help he needs not his medical problems.
Make very sure that the level of pain a task causes him is clearly and frequently stated, if she or he asks your husband to do any physical things like bending to toes or standing if it hurts and he has to hold on to you to do it he must clearly and unequivocally say so.
Finally remember that if the decision is unsuccessful he will have one month from the date of the decision to lodge a mandatory reconsideration.
I would not suggest paying for help with the appeal process you can get free expert specialist help from your local Citizens Advice and I would suggest if needed you went to them for this as soon as you received any decision.