Sure enough, I phoned up the subscriptions department yesterday to check, and heard that a number of other subscribers had reported issues missing. I didn't dwell on whether or not this meant that everyone else who reported their issue missing just wanted a second free CD, but regardless the nice lady tacked on an extra issue to my subscription and asked me to buy this week's issue in the shops as they had no more copies left to send out.
I decided to wait until tomorrow before going out to the shops to buy my copy, and it's just as well I did, as it arrived this morning. Three days late. (*grits teeth*)