I emailed DLP about the book last month and the reply I got was:
Thank you for your email and your interest in Disneyland Paris products.
Disneyland Paris’s book 25Th A to Z above-mentioned is actually in a stock.
To place a mail order, please confirm your name, delivery address, phone number and the credit card details (number, date of validity and 3 last digits on the back of the credit card) from a Visa, Mastercard or American Express.
However, I need a copy of your Dream Annual Pass by mail.
Shipping charges to United Kingdom by DHL are 18.42€.
The total amount of your order are 68.41€ (including shipping charges)
The delivery delay is 8 days upon confirmation of your order along with the payment.
I don't have, nor did I mention that I had, an Annual Pass so maybe it's just for those that do, which would be a shame as I'd really like to buy the book!