I'm thinking even if all the legal elements are met, it still depends a lot on the parents.If one disagrees with having the dog there, for whatever reason,that child would have to be excluded. Possibly more than one will disagree and I can't see how that would work.In my case two pupils parents did not consent to me having my dog there for one hour.Your plan to have yours there more often might not necessarily go down to well with everyone. Just something to consider

Terrible idea in my opinion.
Sorry, I think it's good for children to interact with animals and learn how to treat them properly.

HOWEVER.

what about children who are severely allergic even to the dander that has brushed off on another's clothes?

What if in a split second a particularly spiteful child or perhaps one who has been allowed to act that way with their own dog and therefore not knowing any better hits your dog, pinches it, shoves a pencil up its bum, strangles it in a misguided hug?

What if your dog responds to this by biting?

What if your dog appears unfazed then develops anxiety and fear aggression around children?

What if your perfectly trained, calm and very polite dog forgets its manners and training in a moment of weakness and jumps on a child suddenly, knocking it over?

What if a nervous child builds up the confidence to approach and your dog's friendly excited greeting terrifies them and they are left scared of dogs?

Also, consider how the dog might react to being outside a lot of the day.
They are sociable animals and will want to be with you, in my opinion there is a big difference between being left alone while your owner pops out and it's all very quiet and uninteresting and being left outside while you can hear everyone inside having a great time and your not a part of it.
My dog is happy to sleep in her crate if I go out, but if I lock her away when my son is playing with us or we have guests she gets very very upset.
If your is anything like mine, when children finally do greet it it will be in a very excited, hyper active state and that is not safe around lots of little ones.