I think you're kidding yourself if you think he never drives over limit - and if you're in Scotland that's even less likely. He drinks at home - but how much, when is his last drink and when does he drive the next day? Oh and you more than likely don't even know REALLY how much he drinks.
"Our children do not miss out on anything." My parents trot out this gem - we did! We missed out on extra curricular school clubs, school trips, clothes, activities. We had the bare necessities but that was it. Dad was army so as a result we had friends where we KNEW the dad was on the same pay level and they had and did SO much more than we did.
In addition it's NOT just about the money. We also missed out on stuff because my dad couldn't be trusted to behave at certain events so our family didn't attend.
It also affected mum's ability to do certain jobs as at certain hours/days he wasn't suitable to mind us.
"My children never see him drunk"
A that will change as they get older
B you're deluding yourself if you think he only drinks what you know about.
I say again PLEASE for your DC's sake leave
re pp "it's not that easy" I'm sorry but it is - if you prioritise your DC and NOT a relationship, it REALLY is.