He's now used Blurb to produce a book. Blub is one of those online book-production facilities and in this case use Indigo printers (of which I am extremely fond and which we use for our own calendars). There is an online preview of Simon's book, which is called Beyond Visible Light and I recommend using the full-screen preview to check out the photos. Whether you then buy a copy is up to you.
Also, if you're a member of the London Nikon Owners Group, Simon will be talking about his infrared photography, and infrared in general, on Friday evening (27th April) in sunny South Kensington. (More info on their blog.)