I think the best way in this situation is to start.
Ideas are worthless if they live in our heads. Your plan should be very basic, and mostly focused on how you’ll market the idea.
I’ve built a one-page strategy plan based on the concept of marketing a new business idea. I give it away for free to help people who want to launch quickly. It took me 10 years to really fine-tune and develop based on corporate experiences:
As far as who you need to approach – no one. It starts with you. There are plenty of free resources to launch an idea quickly, all it takes is your sole execution.
Best of luck!