John does have a web site but it doesn't tell much about knapping. He's got a book and video but I haven't watched it so can't comment. His fame is more from the idea of practical archaeology and he participated in the origional dig at Lynford. Where a paleolithic mammoth kill site was found.
John does a great reproduction of the hand axes found on the site and he uses the large hand axes to illustrate knapping technique. All the flakes that occur in knapping are the same. They start out with a conical fracture which forces the flake off the main piece. Whether it's a large flake or small they don't differ in that way. So learning by doing a hand ax first really helps to see what's happening, simply because the flakes are larger and easier to see. And knocking off great big flakes is fun!
There are great videos on u-tube and I've watched tons of them but they still aren't the same as doing it with someone looking over your shoulder.
The States have lots of good knappers who do training seminars, you just have to find one. The hard part is getting good flint. Here it's everywhere but the very best is known as "Brandon" flint and it's jet black and wonderful to work with. It also makes the best gunflints and the houses in Brandon are actually made with flint cores left over from the gunflint making trade. Pretty cool stuff.
Today I made a huge arrowhead, more of a wall hanger or large atlatl point. I was able to make it out of a piece of flint that I had tossed aside as "unworkable" but with my new knowlege from John I was able to rework it and produce something nice.