Might you have any recommendations on some good computer and math books out there for people who are seriously considering going down the self-teaching / self-education route instead of re-enrolling? I'm not a big fan of the college math books we have to purchase for our classes--they don't present all of the steps in an understandable way, and often leave us hanging without the necessary answers out there.
I think that going down the self education route is probably one of the best decisions you could make if you have the determination to learn (which you obviously have by your comments), this can be supported by short courses.
I think its probably better than staying on after compulsory education and being part of the college money making scheme.
If you want to understand why you don't like the current education system then this eleven minute talk by Sir Ken Robinson about Changing Education Paradigms might be interesting.
I would suggest you find a mentor, someone to bounce off, someone you know, who is as motivated as yourself, who can call round and who can work with you or just talk to you about your progress, direction etc.
There are plenty of free courses available to supplement your home learning/discovery.
You already mentioned KhanAcademy which is a great resource, but there are some more involved courses that will also be time well spent:
The Coursera courses are free and are run by organisations such as Princeton University, University Of Pennsylvania, Stanford University.
If you are looking for specific maths courses then here they are.
Another great resource for courses that might interest you is Udacity
I have several books on the subject of self learning/development ( I have around 3000 textbooks !) if you still have time spare after signing on to one or two of the above courses and want a few suggestions for reading material.
I hope this helps and is useful to others on here too.