You'll probably LOVE it! And, if you've already been doing the work for a few years, you will probably be able to teach the instructors a thing or two.
Are you going to learn more, or are you going to just get the degree to do what you are already doing?
I agree that you will be more focused on college than kids coming right out of high school. I often wished I would have taken a few years off before going to college because, honestly, I did enough to get by and that was it. A few years after I graduated, I took a continuing learning class in phlebotomy and aced it (as in 100% thank you!) because it was so good to use my brain again! Also, I didn't have parties and drama to deal with because I wasn't a "real" college student...meaning I was more mature and concentrated on what mattered.
If you're worried about the social thing, think about this. Do you want to go to keg parties? You are probably not the only one that isn't interested in them, and from the way you described yourself, I don't think you will have a problem fitting in. And, you will be one of the ones that show up to class on Monday morning...without a hangover!
Congrats on taking this step!!