You've already got a great start with your manual experience, fixturing, speeds and feeds etc will be no problem to you.
CNC ain't that hard, I'd get a free CAD system, a free CAM system and see what the code it outputs does (you can get a free simulator). You don't need to generate all the G- Code, the CAM system will do it, then go through each code line and look up what they do
Personaly, I haven't manualy coded anything for years- I rely totaly on the CAM output (I might alter a few lines, but that's it).
I love deadlines- I like the whooshing sound they make as they fly by.