AmazonPrime has just been expanded to include free books and magazines. If you have Prime, you can now read all kind of books for the grand sum of £0.00 (thats $0.00 or €0.00, for those of you using funny money.)
Armada Wars books are not currently in the selection of titles, but watch out for them popping up. It's not immediately clear how Amazon will be selecting monthly or permanent titles but as ever time will tell. In the meantime, all the Armada Wars titles can be read for free through Kindle Unlimited!