Based on my experience at a fairly big independent shop, your experience in mechanics and your own bike projects will be a huge plus. Also, most shops are eager to have some gender balance in their service departments.

So, yes, I would apply directly to a bike shop with what you've got. I wouldn't emphasize how much you hate auto mechanics -- but saying you are passionate about bikes and find more meaning working with them is great. Most good shops are always looking for people, especially in the spring. The service departments are reliably profitable, or should be. Put on your resume your mechanical work, your experience with bikes, and your willingness to work flexible hours. The last one is the golden ticket for a lot of shops.

I saw people hired from lots of backgrounds -- college engineering students with no hands-on mechanical experience, motorcycle mechanics, and just general cycling enthusiasts. The people who cared about the work and were willing to learn did great. There are so many different bike components and issues. No one knows them all, and even if one did, new ones come out every year. A general interest in mechanics, curiosity, and a drive to get things right will get you far.

I like the suggestion to keep up on side work, like building and selling bikes. Frame building is a tough business. The successful model is to have first worked for a big famous company, like Serotta, have a reputation for outstanding work, and barely scrape by turning out absolutely gorgeous works of metal. A family fortune or another source of household income and insurance, as another mentioned, helps. I mean, that just helps across the board.

You'll do great -- have fun, take a shot at it, make the bikes sing.