Hi Elidor
If they are currently looking at it, you may be too late to get in any additional information, but you should ring and ask.
If he can't send in any more information, he may be told to put in for a change of circumstances, and they will halt the current process and send your husband a new review form, and then he will have to wait for it to be looked at. His payments would not be stopped - because it's not a 'new claim.'
His other option is to wait and see the result of the claim as it currently stands and put in for a change of circumstances at a later date.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems