Also if you are considering a Hobby level or small business level machine then I can provide you with a days training at our premises for the machines we build and the controllers they use. (UCCNC or MACH3)
This doesn't mean you would be required to purchase one of our machines but it would mean that parts of the training will relate to that software only. However, most hobby level controllers work in much the same way and lots of what you'd learn would transfer to other control software like mach3.
Would also show you the CAD/CAM side of operating a CNC machine and the process of creating the G-code files which run every CNC machine.

Once you have the basics shown and understand a few basic principles along with learning the process of how to create a part from start to finish then things fall into place quite quickly. The actual process of setting up the job and running the machine is quite simple.
It's common for people who have no expereince to be very daunted by the control software and all the many buttons or screens, so believe it to be very complex when infact it's simple to setup a job and cut the part with just 3 or 4 button clicks, and that's just the first part. If your cutting multiple sheets of the same part it becomes a 1 button click affiar.

The real challenge is creating the part in the first place and that mostly boils down to your imagination along with learning the CAD/CAM side of operating a CNC machine. This is something a collage or course could provide. However, most people learn by trial and error along with watching the 10,000's Youtube videos out there.