I wish it was easier to learn beyond the really basic "igneous, metamorphic, sedimentary" stage. Like, I have no idea what all is underneath me right now or why, and if you research it you're instantly wading through papers written about some specific question, which assumes I know this or that craton and it's history.
There's a few levels down from each of those that you can get the broad strokes of fairly easily.
For igneous, you can broadly break it down into extrusive vs intrusive. Basically, did the magma slowly solidify underground, resulting in large grains like in granite, or did it come out in the form of lava that cools rapidly into fine grained or even glassy structures like obsidian. Then there's the other axis of "how much silica is in there?" Really high silica content rocks are called "felsic" rocks. Granite is an example of a felsic intrusive rock, ryolite is an extrusive felsic rock; Basically the same minerals, but way smaller crystals. On the other end of the silica spectrum, there's "mafic" and ultramafic rocks that have less silica and more iron and magnesium. The main example of a mafic rock you might know of is basalt. You can find charts like this one that break things down that way.
Cool diagram! It's interesting how narrow the band of distinguished composition differences is. Anything above 69% is just felsic, and anything below 45% is ultramafic, and hasn't been created any time recently because the Earth has cooled inside.
Structure-wise, for igneous there's various different kinds of intrusions. For metamorphic and sedimentary there's (of course) layers, as well as faults and folds, and pedosphere formations like drumlins. And then there's other kinds of intrusion (if that's the right term) like salt or various kinds of petroleum.
What I'd really love is geological history laid out on a timeline for some specific area. I'd like to be able to picture it all, instead of just looking at isolated examples of a rock or landform.
Don't overthink it. Look up faculty and try to find one that teaches introductory courses. Send them an email stating something along the lines that you're a non student looking to learn a little more than high school introductory terms. Ask if there's a lecture you could audit or a time like office hours where you could ask questions. A bunch of professors would probably be willing to talk to a flat earther if they were approached on a polite and courteous manner.
If your interest can't be satisfied with a question session, you could look into whether a local university has an option for non-degree students to enroll in classes. That's an option that's frequently not advertised but is pretty common (at least in the US.)
Some community and state colleges can be pretty cheap, and most schools offer night classes for those who work all day. A gen-ed like geology is likely to have such hours available for this community of night students, especially if you live in an area where geology is related to employment. Usually pretty cheap to take one class at a time through something like an Adult and Continuing Education program.
To be clear, I'm Canadian. As far as I'm aware big-boy institutions are the only option. They're cheaper than the US ones, especially if you stay in province, but it's still hundreds per credit.