Thanks very much for your good wishes. I think it's lovely of you all to bother to post.
I've been at work all day, but it was a good day, as our bigger year 12 Physics set (18 of them) were on the last day of their individual projects. Most of the projects have gone well, and several of the students thanked me (as you can imagine, it's a lot of work getting apparatus together for them, ordering components, etc), so it made all the effort seem worthwhile. Mind you, the next set starts on Wednesday, so I can't exactly relax yet!
Then I've spent almost an hour talking to my daughter in Moscow on Skype, which always cheers me up, so all in all it's been a great birthday so far. We're having a quiet evening in, and I'm cooking sirloin steak soon, so should be good!