I will send you a typical barn survey report to give you some ideas however surveys could be categorised in order of preference as follows :-
1) Drive by - take photos from all available angles.
2) 1 hour survey - drive by plus measure key dimensions as follows :-
length (of/of) breadth (of/of) height (us sill/towp) + towp / peak No of bays length of each bay ref f/f make general notes including type of frame construction. take as many digi pics (1mb) as possible.
3 Detail survey
as per 1 & 2 plus measure everything possible including typical timber sizes typical joint types typical peg sizes