I need some help writing a business proposition letter, can someone help me out?

I am writing to the local council to propose an idea I have to hold a live event in a potential historically sensitive site, so far all my live events have been in hired venues so I can just concentrate on organisation and marketing that I know, but business propositions aren’t my strong point. I need to convince the council that this event would be in their interests to promote the cultural reputation of the city that the council tries to promote. I have a draft and would be very grateful if someone could look over it for me and form into a good proposition. Thank you very much