The delivery companies are told not to return the delivery to the depot, Clive, so they will always leave it if you're not in. You can also specify, when you order, a 'safe place' for the delivery to be left, if you are likely to be out.
I have placed an order tonight, for delivery at the end of the month, so that gives me a chance to make some room in the freezer, but I still get the special offers.
As for the dry ice, yes, I have experimented with chucking hot water over it in the sink, and it's quite fun to play with. Not sure I'd do the rubber glove thing though. I hate balloons, and they always make me jump out of my skin when they pop. Strangely, though, I can sit through the most harrowing, jumpy horror film, without a flinch! Must be my sadistic nature.