Nice looking website, Ian. Clean, simple and straight-forward. Just the way I like it.
Might I suggest, though, some links? I noticed that in your "Books" sections, while you have a respectable amount of information about the pricing (both US and UK, as well as ebook), there were no links to help people along the way.
I would suggest that, instead of merely providing information and then having potential customers search for the actual books, you should include links to, say, the relevant Amazon page where they can be bought. This is even more important for the ebooks.