Thank you both for your input. I think I can draw the conclusion that there is no British book that covers seaplane flying. I am aware that seaplanes are much more prevalent in North America, but I just wanted to know if there had been anything published in the UK since a book written from a British perspective would be of greater value to me.
I have been working with a seaplane company for a few weeks now and I'm slowly picking things up. Maybe I can write the first British book on seaplane flying in a few years time...