Welcome to back John! Well there's no reason why you can't do both. That is, keep up your hand drawings and scan them in, and try experimenting with GIMP to touch them up digitally. You are right that there is a learning curve with GIMP, but you can actually learn quite a bit about how to use the program just by doing a few of the tutorial walk-throughs here. At any rate, you don't have learn it all at once either, just play around with it when you have the time.

Cheers,
-Arsheesh