Interest from a Large company

I submitted an idea to Proctor & Gamble yesterday, and they responded right away with interest (not in the 3 month normal respnse). They are very interested in my product/idea. I am at the crossroad of needing drawings, patent, and $ for those things. The prototype can be had for very little as it is a simple product design. I want to file the prov. patent myself, but am unsure of the sucess. Is there anyone that offers collaboration on these types of deals? Thanks