The dihedral on the LT-40 is fine, and in any event, changing it wouldn't affect a tendency to climb. The LT-40 does normally need the elevator trimmed so it's down a fair amount. To change this, you'd need to fiddle with the wing or stabilizer incidence: not advisable for a beginner, and not necessary anyway.

If you have a tendency to climb in straight ahead hands-off flight, you can trim it out. If it's just climbing when you come out of a turn, that means you're holding up-elevator too long.

Simulators are pretty good for practicing the left-right thing. Not a lot else, at least for me; especially not takeoffs and landings.