It sounds like you’re asking for advice too late tbh.
The dog at school is an adult. You’ve not seen what the puppy phase is like. You’ve not experienced the biting, nipping, weeing and pooing everywhere, ripping up toys (and I don’t mean their own) and so on.
Cockerpoos are cute, but have 2 manic breeds mixed! I have 2 working type spaniels. The youngest is 9 months and I’m just through the biting stage. Toilet training I was lucky, she nailed it quickly. However she is awake every morning at 5am, and whilst she does sleep through the day, when she’s awake, she’s very awake.
There’s an element of fault with the breeder here for allowing a puppy to go to a home with young children. For both my dogs (different breeder) it was like having an interview, so they could ensure their puppies were going to the right home. I have now young adult DC, with what I’ve been through twice in young puppy stage there’s absolutely not a cat in hells chance I’d have done it with young children.
Good luck, I suspect you’ll need it.
Oh - and ditch the puppy pads. Outside every time, every half an hour, and after every meal. Whatever the weather, and you stay outside until they wee or poo, then praise.