There a couple DIY upholstery books published by Singer that might be a start. What about your local community college-perhaps there is a continuing-ed class on upholstery you could sign up for. But do you ultimately want to do upholstery yourself-could you contract that part of the work out-especially if your business grows.
additional 2 cents:
It’s not absolutly necessary though, you could skip the schooling and do exactly what the newly minted graduates do: put your portfolio together and hustle your ass into any/every show you can. After you get enough sales, a gallery should pick you up.
I agree
I would also agree with IP_wirelessly. It sounds like you’ve already got some know how and a good resource in your father. In addition to galleries, search out small local owned home accessories stores. I respectfully disagree with trying to sell at swap meets-people who shop at those events are looking for bargains and may not appreciate the level of craft and attention to detail that your work deserves. Seek out the shops or boutiques that you want to have your work associated with.
How would you characterize your designs? Hand made, one of a kind? Honoring craft traditions? Contemporary? Designed for small production runs? Mix of materials beyond wood? You also my look at http://www.furnituresociety.org/furn/ as a resource.
College will allow you to explore form and materials beyond what you already know. If your sketchbook is packed with ideas then I would agree with your initial plan to try making a few pieces and test the market. Those pieces can then become portfolio pieces for college applications.
BTW, are you looking at undergrad or graduate programs? I’ve gone the furniture based grad school path. If I can offer advise in that area-send me a private message.
Good luck on setting up your own shop!