I think what Wishstar meant was you need a notorized copy of his passport, or his actual passport. My husband sent a notorized copy of his when we sent in my fiance application. Oh, and an original copy of his birth cert. I remember that we had to take all those same things with us when we went to Croydon to apply for FLR.
I am a bit confused,, I take it you two are getting married here in the US, and then you are going to apply for your entry clearance and spousal visa in New York? If so, it may be good for you to go together with his documents?
EDIT,, don't forget to have him bring proof that you two have a place to live in the UK,, deed to the house, rent statements, utility bills, phone bills,, the more you can bring the better
