I purchased my set ca. 7 months ago, and did so simply by emailing
[email protected] and requesting a quote. I was provided with several different options (plastic/leather binders etc), and had the set 2 days after confirming and paying by credit card.
The alternatives are to purchase Airservices docs from their
website, which has an online store option, or to print off the required pages from the Airservices website and to store this in a folder on your own, however you will probably find this troublesome.