Wow Lynsey, that's quite an undertaking! While I don't have any rock solid info for this post, are you asking for primary contractors or primary and their associated sub-contractors?
I would think that GU would have comprehensive information but you could also try Maritime Archives and Library at the Merseyside Maritime Museum, Liverpool and the National Maritime Museum in Greenwich, London. I have been researching drawings for an eventual model and these are the repositories of info that I've found thus far. Perhaps they could be of some service to you.