I found these $1 stamps just before I left the US, and love them. It is great to find stamps with amusing sayings for such a good price. I am sure they are available in the UK as well (and that the cost will be a little more than 50p!) Not sure if you can read the saying on the owl card - it says "Follow your dreams, except the one where you're at work in your underwear!"
Fun and laughter wasn't the only thing I got from playing with Max at the weekend, I also picked up his head cold and have felt totally rotten for the past couple of days. A summer cold always seems so much worse than a winter one - no snuggling up with a hot toddy to make you feel better whilst the snow falls outside the window (or in the UK, the rain!)