I think you need to consider where you want to end up.

If you learn to fly on a 3 channel park flyer, you can do it on your own (I did), but you won't be ready to just "move up" to a gas-powered trainer. You'll be better prepared, but not fully prepared.

If you start on a glow trainer, you should get an instructor, but once you're soloed on a glow trainer you should be ready to start advancing on your own.

On the other other hand, if you stay with electrics, you can move from a parkflyer to an "aileron trainer" and move up from there.

Anyway, have fun...