I’ve noticed that the book is now listed on Amazon.co.uk.
The details for this listing are taken from the data I submitted when I registered for an ISBN, not from the details on Lulu.com. This makes me think that it was perhaps unnecessary to register the book with the Lulu.com distribution services, which demand that I increase the price of the book to £8.99 so Amazon can benefit from the sale!
There are lots of options for the publisher (i.e. moi) to add images and extra information to the product page, so that’s another task for me to complete at some point. While I am doing that, I will attempt to register myself as a third party vendor of the book, and see whether that results in a cheaper cover price.