Most of the time a blind eye is turned. I'm still of the opinion that the smoking ban isn't really about stopping smokers from smoking. It's more than that, it's playing the long game, it's about making smoking socially unacceptable so future generations don't even bother starting.
Just going by NHS stats the adult population who smoke has dropped from 40% to 20% in the past 40 years. It's dropped from 27% to 20% since the smoking ban was introduced in 2007. Heart attacks are down by about 10% since the ban. Childhood asthma has gone from rising year on year before than ban to declining year on year since the ban. Now obviously all of these trends aren't simply due to the smoking ban, lots of other factors are probably responsible too but it clearly is a step in the right direction. There will always be a group of people who choose to smoke but what if the percentage of smokers drops to 10% in another ten or twenty years? Surely that is a good thing for the health of the nation?