The old saying of "Snooze you lose" springs to mind!
I was going to sign up for the Vätternrundan in Sweden. If you don't know, this is the largest recreational bicycle ride in the world with a 300km ride around Lake Vättern with 21000 riders (+ 2000 Swedish Classic riders). It sold out in 2 hours 45 mins.
The moral of this story is, don't agree to look after the kids (school inset day) when there are more important things to be getting on with.....