Hi paul
I know this won't help your quest to find books by UK authors, but have you seen the two books by Michael Byrne? He has two very good books and dozens of articles from Fine Homebuilding, Journal of Light Construction, and other mags. While some of his writing is quite specific to trade practices and materials sold and used here in North America, you would find a wealth of info that is not specific to any market but instead is just good, solid trade skills that will benefit any tilesetter around the world.
When I started out in the tile trade, Michael Byrne's articles and books, and to a lesser extent the first of John Bridge's books, were my sole resource. The Tile Council of North America manual was another, but that was about it.
Michael has another book coming out soon, and it is supposed to be a blockbuster. I've talked to him about it on the phone, and from what he has told me it will be a very good book for the professional tile setter, regardless of country.
I think most of the guys here would do just fine in the US and Canada, once they had a few weeks experience to get acclimated to the different methods. And I think the same goes for some guys I know here, if they came to the UK to work.
A good tradesman is a good tradesman, regardless of where he is working.
Give Michael's books a try--I think you'll benefit from them.