Everyone has said go for it so far, and I'm going to agree, with a little more advice.
1. Buy a boat that is ready to rock, not a fixer upper, telling yourself you and dad will work on it for a few months then get going. You probably won't. So buy what you can that is ready to go now.
2. Make sure you get a good marine surveyor to go over the boat with you, these guys see problems that you wouldn't even think about.
3. Read up a little bit about provisioning, buy lots of spares (stuff breaks all the time).
4. Wherever you're planning on launching this adventure from, start, by getting to know people in the yacht club, see if you guys can join in some bay races, maybe with some experienced people showing you how to do things. Then start going on farther and farther away from the dock. Don't make a schedule, you'll know when it is time to leave for good.
5. Have fun!