Central heating dilemma

Does anybody know anything about boilers? My pilot light is on but when I try to set the heating or water to constant nothing happens. Sorry to be a pest and ignoramus but your help would be appreciated. You can tell me a joke along the way (or make one at my expense, I'm too cold to object.)

do you have a carbon monoxide test thing? Anything wrong with the boiler could lead to carbon monoxide being released. I'd test it before doing anything.

Yes, thanks for that. It's ok, but I will keep my eye on it.

Do you have 'myson' thermostats on your rads?

Um... I don't know. All I can tell you is that it was fine yesterday.