First of all, I'd strongly suggest that you do this on the side for at least 6 months. Making a living is terribly important these days, and all the benefits of your present job have to be figured in. Remember to write every single thing down that you spend money on, and every penny that comes in and what goes out. And every cent that is paid by your company for everything, medical, etc besides wages.
Talk to a lot of the long arm folks on this forum, then go visit one and ask some sharp questions. When you quit a job that pays real money, there are masses of other people who will fight to get a chance to be hired, and it's unlikely you would ever be hired back in the same company.
Then, if your mind is made up and family, if any, are agreed, then go with your dream and work at it.