That book is an excellent place to start. It's geared towards very cold climates but it also helps understand things from the bee's perspective. Here's Leo's website
https://horizontalhive.com/index.shtml which is also informative.
"Organic & natural" bee classes seem to be rare. I think Leo's would be excellent. Michael Cox runs a treatment free group on
Facebook. Check his bees posts here at permies for that address. I suggest taking a beginner
class from your
local beekeeping organization & when they mention chemicals ask them about alternatives. Read some of the other permies bee threads too. The forum is not a class but it's natural & organic.
In my opinion &
experience ... it boils down to starting with strong locally adapted bees in a nontoxic environment with plenty of bee food plants around. Then observe them carefully but mostly leave them alone. Survival of the fittest.