Just a thought, Matt, your kids will need to travel to Canada on Canadian Passports - they can't travel on British ones as they are Canadian Citizens.
https://www.canada.ca/en/immigration...it-canada.html

When we registered our kids at school, we had to show their Canadian citizenship cards along with their British birth certificates to show they were legally able to live in Canada. The school secretary said I would have to show their immigration paperwork (which didn't exist since they were Canadian citizens) or their citizenship cards.

Years before we moved, we had an appointment with an immigration consultant who told us that when we were entering Canada with the intention to stay permanently, the kids and I (Canadian) would have to enter on our Canadian passports not the British ones. Since then, like Siouxie mentioned, it became law that all Canadian citizens have to enter Canada using their Canadian passports. When I applied for citizenship cards for our two youngests kids, I contacted Canada House in London and spoke to a lovely, helpful woman who was able to get their cards rushed. We had them within about 3 months, rather than the 11 months it took for our eldest. So maybe try that. Best of luck.

What Siouxie says. Dual Nationals cannot enter Canada on their British passport as you need a ETA which you can't get if you are a Canadian citizen. QED you'll need to apply and receive Canadian passports before you move over.