Some other ideas I remember seeing here are to plan something you would enjoy, maybe takeout food and a Netflix movie, or lunch with a friend, or anything else you might think of, at the same time or on the same day as the missed appointment. People have also had their T's write them a short note on a post-it, or even write them a note or card to be opened while they are away. Personally when I miss my T I re-read our emails (and my T is very very brief in email replies but it still helps). If yours would call and leave a supportive voicemail, that seems like it could be really helpful to have and to listen to -- if they're willing. And like ElectricManatee said, some small thing from their office might help if they'd offer to let you borrow it; or even a photo of their office might help.

This is a great place to find support too. I think at times we've had whole threads for people dealing with T vacations (like in late summer or around the holidays).