In the nicest way possible, you need to wise up a bit. Yes, it would be lovely if everything could be friendly, but in my bitter experience, once you start getting down to the nitty gritty of a separation, people can turn very nasty.
You need to protect yourself financially. You say he earns more than you? You really need to be the Resident Parent, and I'd be pushing for the kids being with you 5 nights a week, 4 at a minimum, so that he has to pay child maintenance. There are so many things you will need to pay for, for the children, that are more than food & a warm bed : books, school trips, shoes, uniforms, clothes, vaccinations, presents for friends parties....the list is endless. It would be impossible for you to calculate all that you spend, and then demand half from him.
Also, even if he is friendly now, be prepared for a giant U turn, when he gets a Girlfriend. My ExH paid maintenance on time, until a new woman came on the scene, who had 2 kids of her own, who she wasn't getting maintenance for : he suddenly stopped paying, as she had his ear. It's amazing what men will do, for a Partner who is servicing their dick. Harsh, but true.
If he has a Pension, you need to get recompense for that in any settlement. If you leave the home, and set up a new one, you need some sort of payment to recognise the fact that you have to furnish a whole new house, and he doesn't (costs thousands).
You really need to look out for yourself here, and not be a walk over. In 10 years time, when you both have new Partners, you'll regret it if you didn't get the best outcome for yourself. Especially if he is able to treat the kids to things, like holidays, whilst you are struggling to get by.
The one thing though that struck me, is you said that even though he works longer hours than you, he does most of the childcare? I don't understand this. Why?