There are lots of "name brands" of NH that are popular here in the US... here's a short list, most of these trainers have home study systems that are fairly readily available online, or used via eBay
In no particular order, except maybe most publicized:
Pat and Linda Parelli
Also, I highly recommend reading some of the "old time" masters of what came to be known as NH: Tom Dorrance, Ray Hunt, etc. These guys provide fantastic insight into the whys of training, above and beyond the step by step processes that often focus on method and results.
As Crimsonhorse said, there are tons of NH trainers out there, do your homework and figure out which one suits you, the horse, and your goals.