Don t waste any chances, if you have a business plan already, present it. this might be the right time. Always GO, go, go..you will not succeed if you will miss the chance. Business plan is important so that you have a basis on how to discuss your idea, its feasibility etc..
I think you should wait until the Director has given an opinion on the viability of the idea. If favorable, s/he will be on your side as you move the idea up the food chain . If not favorable, your battle will be nearly impossible to win. At this point your idea needs strong allies before a comprehensive plan can be written.Good Luck!
A business plan shows that you have thought through the business idea and understand most of the business aspects thoroughly. I would recommend that you take the plan with you. If you would like some ideas on writing a business plan, check out the site below.
Take the plan with you - it shows your enthusiasm for the idea.