I've just replied to a pm on this topic....this is the gist of what I said.
Re: Moot and kids, a good idea?
Hello

The site is massive. It's on sandy soil and even when it pours the ground dries quickly

There are some things organised for families and children, the beach is a fair walk, but it's in deep sand on the way, and you can just stop and let the kids play.
Usually they make friends easily with similar ages, and their parents, and the week just disappears.
I'd take spare small tarps or cloth, and paracord or similar, and make play areas for them, tents, tepees, that kind of thing, and if you take a couple of small spades or trowels along, the kids can dig to their hearts content even if there's nothing else happening for a bit, but Mum and Dad need a sit down and a quiet blether
Bushcraft has it's own protocols, good manners kind of thing, about not asking to use someone else's axe, don't pick up someone else's knife, don't hand a knife back point first......a lot of folks take it ill out and start talking about moaning and nazis when someone explains. It's neither moaning or nazi like, it's simple explantion that keeps everyone happy.
It's the same kind of thing with children.
The fact that you've asked me is the surest certainty that your children aren't going to be a problem for anyone

Basically please see that they don't touch anyone else's tools or guylines/hammock/tentage, and that they know not to go near someone else's fire, and that's it really

Oh, and the primary rule for little ones, enjoy being in the woods with their parents
Genuinely, the Moot is a family friendly event, Tony has young children of his own along, and the baby was literally a baby last time, and they are all brilliant to have around

There are usually craft workshops for children, Shelley and Lorraine do others, and the slightly older children are welcome to learn to do things like the firebow. Adult workshops usually have a couple of kids tagging along with a parent. Capt'n Badger does a brilliant treasure hunt/ all over the site adventure for the children too
There are a lot of individuals come along as well though, and they don't want to be fussing over whether or not they can leave their axe next to the woodpile, just incase a child comes by and picks it up. They don't want to have to put their fire out when the soup's slowly simmering when they go to the showers.....they shouldn't have to. Children and other adults ought to know better than touch someone else's kit or fire. It's just simple courtesy really
Does this help ? It really is a brilliant week for everyone and I'd hate to discourage you in the least.
cheers,
Mary