You sound like you really want to learn how to fly, so I agree with others in that you're fine to start with the A-10C, even if it's overwhelming.
I would actually advise against learning on FC3 aircraft. In fact, don't fly FC3 ever. That's my radical opinion.
The beauty of DCS is that you can learn an aircraft and it's systems as they are in real life (or at least extremely close to).
I'd recommend learning on an aircraft with no HUD, so that you get in the habit of relying on the analog gauges from the start. The L-39 is perfect for this, and it's a trainer, so it's quite appropriate. I think that's important, as you seem to have very little experience in aircraft controls and need to get the hang of the fundamentals.
Once you have that mastered, the A-10C will be a breeze to fly.