Hi James, I went a bit mad and bought all three when I first got into urine therapy a couple of years ago tho as you say there's plenty of info on the net.
I think The Golden Fountain (Coen van der Kroon) is the best of the three in terms of accessibility. He goes into the history of UT, applications, how to treat various ailments etc, and discusses hypotheses as to how/why it works. There's even a photo of him with a wine glass (obviously not full of wine) making a 'Cheers' gesture, lol! I'm sure he has a website but I never found it.
The Water of Life is mainly a book of case-histories of people who recovered from varous illnesses even cancer, doing UT to the extreme. Some amazing stories.