Matthew:
The most important distinction is whether you are going to publish a coffee table book for people to look at, or a book for people to read.
If it's a picture book, then the photographer will be (and should be) making most of the money from it. There are LOTS of coffee table books about golf courses (including at least three about Irish golf courses), and they are all judged by the pictures, so to compete with the others you have to do it better visually (or have a stronger distribution network).
If it's a book for people to read, like Scott's, then the photos are secondary and meant only to illustrate the text. In fact, it would be better to limit the number of photos and try to keep the price down for the potential golfing tourist. The goal should be to draw attention to the hidden gems of Ireland which would round out the tourist's itinerary, although obviously you would cover the big and famous courses, too. [There is a similar book for Scottish courses by David Hamilton, which I think has done reasonably well over the years.]
Overall, it is a tough market to crack. Most true "golf course architecture" books sell less than 5,000 copies and it's difficult for anyone to make a profit on that, because at that expected level of sales, no one is going to spend a lot on advertising the book to try and sell more. Unfortunately, that's why most of the new books we see are coffee-table books which are forgotten as quickly as we look through them.