I used to be an IT contractor and was on a very good salary for quite a few years. However, it also meant a lot of long days and lots of travelling. I loved it and the money was great - me and the wife really enjoyed it and went all over the world!
However, once we had a child I took a job at a local company and took a big pay cut (about 50%!) as I wanted to spend more time at home. The way I looked at it was that I could always go back to earning contractor money if I wanted to, but there was no way I could earn the time I'd spend with our child.
To cut a long story short, it was the best thing I did. The family life balance was brilliant - the energy I spent driving an hour to I got to spend with our child and I've not wanted to go back. Watching sports lessons, games, piano lessons, Christmas carols etc and the rest are priceless! You will never, ever, ever get that time back and you'll be amazed how kids don't listen at all to you, but do really. If you're not there, you won't understand their hopes and fears and they will listen to someone else. Being there for your children is the best gift you can give them.
One thing I'd say about overtime is that it's great when you get to pick and choose, but if it becomes something you HAVE to do, you'll hate it. Imagine being the boss when you can't get people in and you have to do it regardless - it goes from being a nice to have to a real chore.
I don't know your trade, but if you are handy with the electrics which it sounds like you are then I imagine if you wanted to you could easily make a fair few quid doing "foreigners" if you were stuck for money anyway and I bet you'd make up any shortfall very easily! Try getting an electrician round to do small jobs!
My advice would be to take the pay cut, you won't regret it.