Community college would be ideal. If you are highly motivated, you might be able to get the textbooks and "teach yourself", but you wouldn't have access to the labs (or the instructor, or the other students, etc.). The labs would be useful, because they would allow you to get your hands on an oscilloscope, and some other equipment that you probably don't have at home. (You can buy a multimeter, and you should.)
There's enough information on the Internet to learn just about anything (if you know what to look for), but most of us learn better with the structure, guidance, and feedback we get from taking a class.
As you can see from the course sequencing, you generally learn all of the basics before getting into microprocessors. But, there are plenty of people here playing around with Arduinos who have little or no electronics background, so it's not absolutely required.
Probably the most important things to learn are Ohm's Law, Kirchoffs Law, and the basics of how the basic components work (resistors, capacitors, inductors, diodes, transistors). Once you have that background, you should be able to "pick up" the understanding of more complex circuits & integrated circuits.