When writing a business plan you sometimes end up locking yourself away. You might have unique ideas which lead you to seek some isolation and secrecy, or if you are going to be a sole trader you may only have one person to consult namely yourself. But it is fantastic to try and get broader input on your business plan _ whether from a professional, or simply from friends and family whom you trust. I say that because of course you need to be careful with commercially sensitive ideas, as you do not want to pass your plan on to someone in the pub who then starts your idea before you across the road.
No doubt there would be a lot work to do to do a plan like this. You would need to figure out how to put it all together, do all the calculations, do a lot of what if's, etc.. And I'm sure one of the biggest things would be, would you actually take the time to do something like this or even have the time to do it? You could pay someone to do it but that would probably cost you a lot. Plus if you did that, most likely it would require a lot of back and forth work to get it just like you wanted it which would be even more expensive. But even then, would you spend the money to do it? There is a better way. If you would like to develop a nice plan like this for yourself and give yourself a good shot at making your life better, then find a planning software that does it all for you.