http://www.scorra.ca/ Lots of riding in Simcoe, some in Halton.
Trailtours does a great job of off-road teaching/training in the Ganaraska.
You don't need a KTM to start trail riding. Go cheap and easy with an XR250, CRF230F, KDX200, TTR250, etc.
Plenty competent, cheap to buy, cheap to run.