You will need to show the inspector you have thought about the dog and the children's safety around them... you can do this in a risk assessment.
It is best to be totally honest with yourself and accept that even the most gentle, docile dog might nip a child if provoked / poked with a stick etc and you can't be everywhere at once... so I would show how you intend to keep the dog well away from the children when you are working...
I know of some minders who have been told to keep dogs in separate parts of their house or in cages (one was 5' high if I remember rightly) so don't take anything for granted...
Good luck with the pre-reg! It's an information gathering exercise from both sides, so have a list of questions ready