I can't get to the page through your link Guy, but I'm pretty sure we did the equivalent of the one day course while at College...Merrist Wood.
We touched on a lot of the stuff in the longer course during our training and had to do a tree inspection practical as part of our exams.
The stuff I learned from Jack Kenyon on tree inspection has been invaluable for me in my career. I have not gone into much more detailed depth with it, but the foundations laid were pretty solid.
I guess you'd have to decide if the expense of travel and fees is worth it for you, but at least it is a Nationally Recognised qualification.
I'd also Google where it is being delivered, and who is delivering it and check their references...some people are better than others.