Stumbled across this late--what did you wind up doing? Here's my perspective, assuming you are on your own:

I taught myself on a Cox .049 powered Schoolmaster which had a 39 inch wingspan, and I had a great time doing it. I flew 3 channel planes for years before I got my first aileron plane. Years ago that was true of most RC pilots because servos and extra channels were very expensive, so most people started out simple. Now we're seeing the same thing again with people starting on simple park fliers. It is a fun way to learn because you are not tied to an instructor.

Gradually learn to handle some wind. Start by making S turns into the wind and keep allowing the wind to bring it back as you fly at right angles to the wind. Don't try turning downwind until you are comfortable doing the S turns because a light slow plane can get away from you very fast on a downwind turn.

The transition to ailerons is an absolute non-event, once you are comfortable flying on three channels. Do things in stages. If you go straight to a .40 powered ARF with just a little stick time on a park flier your plane might not survive the first flight. Just take your time, go slow. Build a Butterfly, get used to it, then shorten the wing so it's faster. It's all about having fun and not going too far beyond your abilities at any stage.

I'm amazed at people who think they have to have ailerons. I guess it's all they know. With a three channel plane you put the rudder on the right stick. Then, because of the dihedral, the right stick really controls roll just as it does on an aileron plane. The only difference is which stick you do your takeoff runs with. That's a minor transition. Later you can learn how to use the rudder on an aileron plane to do slips and such. Step by step, enjoy every step.

Jim