Trying to start a company without any actual experience is asking for disaster. But
https://www.amazon.co.uk/Budget-Book-Film-Television/dp/0240806204
https://www.google.com/search?q=real+budget+for+film+example&oq=real+budget+for+film+example&aqs=chrome..69i57j0i546l3j0i30i546.9730j0j4&sourceid=silk&ie=UTF-8
And I'd look at Stephen Follows site.