@simonbuttress
How does all this work? simple if you know it. I will try to explain.
1 - Download
calibre on a PC (Windows/ Mac or Linux)
https://calibre-ebook.com/
2 - add e-books to
calibre through the gui menu. Then close calibre.
3 - copy the directory with the
calibre database and the e-books in subdirectories to your Raspberry Pi.
4 - point COPS to the directory where you copied point 3 to.
5 enjoy COPS
Do not forget to protect your e-books from unwanted visitors with a password.