Could you not regisiter at Debenhams, or The House of Frasier,, and slip a card in the invitation saying where you are registered, with the website and phone number? I got an invite last October for a couple that I know online, who were marrying in December, and their invitations had a nice little card, done in the same style as the invitation and rsvp card with that information. I don't know how this is in the way of wedding ediquett,, but since I live 6000 miles away from them, I was grateful for the info, and the ability to send a little something from their registery list.
One thing you could do, is instruct your parents (if they are asked by others) to let them know how difficult it would be for you to transport any gifts from one country to the other,, and suggest a gift of money, or a gift certificate.
Best wishes, and good luck