So many times over the years of playing I've said, "thank goodness for free sheet music". Truth is, without free sheet music I wouldn't have learnt half the repertoire that I know. In this growing page I provide access to some of the scores that I've worked with and, if you click here, to a list of the top free sheet music sites for classical guitar.
You'll need to go a little deeper into music theory as you proceed. The best online resource for this is Guitar Theory Revolution. It recognises that music theory is very hard for guitarists because music theory has till now been located in the piano paradigm. The Guitar Theory Revolution overthrows the piano paradigm that is holding you back and embraces the attributes of the guitar to unpack music theory. In fact, it goes further and allows you to see that the guitar is one of the best instruments for learning theory.