Just wanted to say (in addition to Well Done!) that moving a child at the start of a school year can be overrated. Kids are keen to see their friends at the start of a school year so the new kid can get a bit lost and that makes it harder to make friends.
Mid year you're a novelty so they're more likely to make an effort. It's swings and roundabouts but don't worry too much about the timing is my point.
Also although Primary school is important, I'd say they're are more good ones than there are great high schools so I think that should be your guide.
If you are going to want to move, do it as soon as you can whilst he's still feeling guilty and also so you're not then upsetting the arrangements that you've put in place in regard to the children. Do it now when the arrangements are all up for grabs and determination.
And some legal info from a family lawyer:
Child Arrangements: most are one resident parent. Non resident parent gets every other weekend F - Su and a tea-time contact (one early evening after school in the week) in the other week.. Most but not all. You have to get on well really or at least very civilly for 50/50 to work.
If 50/50 is right for your family it's better for the kids to go with alternate weeks.
Arrangements for the child to spend mother's day with you, father's Day with him regardless of which week it falls on.
Arrangements for the non resident parent to spend time on each child's birthday.
Half the holidays - either half a week each at half term or eg one gets October hols, the other gets Feb and whatever you can sort for May. Get it in stone early on.
Easter hols are a week each.
Summer hols 1 week parent A, 2 weeks parent B, 2 weeks parent A, 1 week parent B. I'm afraid it means holidays need booking well in advance and if you can't both be flexible then they get fixed in stone.
Christmas either alternatively or the kids do morning with one and afternoon with the other (personally I think the former is better for the kids. Insisting the kids spend time with both on Christmas Day is usually putting the parents' wants before the kids).
In some families one will move to celebrating the continental way and having presents and a special dinner on Christmas Eve. You might want to consider that and also consider whether you want NYE as a special family time or you'd rather be able to go out and party whilst the kids are with him.
Obviously if you follow a different religion then adapt for any festivals that are important to you.
I would also suggest you either invest in an app for communication. There are several. Family Wizard is a well known one. You can also though just set up an email address that's dedicated to communication with him. Use that to send photos and provides updates and send on school info and parents evening appointments arrangements etc. Don't use your personal email for communication. This way means you can switch it off if he starts being abusive/harassing and only look when you want to. If it's your personal email he can just invade it under the guise of communication about the children.
I would always always get the above sorted and agreed and WRITTEN DOWN both of you sign it.
You don't need a court or a lawyer as long as you consider all the above including how handover and pick up will work and the time of day for those.
You should put in "the children will live with the (resident parent)" and "(the resident parent) will make the children available to spend time with (the non- resident parent) as follows:"
And then write out what you've agreed.
And, obviously, keep a signed and dated copy
From what I've read, you have very much got this. Please keep us in touch every so often. I feel quite invested!