Without knowing what job he is going for Daffy, it is difficult to say - would he perhaps be applying for a job that requires him to be an "Approved Person" as far as the FSA is concerned? That certainly means that they need a lot more info than normal. I would guess that the landlords info would be so that they can verify his residency and the doctors maybe so that if offered the job they may want a medical report. The CRB check would probably not be any good to them in terms of the things they need to check and from memory, I don't think they are allowed to take another institutions word that they did an identity check, I think they have to do their own.
If he isn't comfortable about providing the info now, he could say that he would be happy to provide that after interview if they were considering him for the position. I don't think that is unreasonable.