I'm wondering the same. I have kids of 4 and 8, and I don't want to tell them about the surgery. But I guess I will have to say something about mummy eating less to get a smaller stomach, to explain the weird eating habits.
I have got a late time of day for surgery, so I will follow my kids in the morning as usual. And then tell them I go on a trip or see a friend or something, haven't really desided. I think I will call in "sick" when I get back from the hospital the day after surgery, to get som slack in recovering. Luckilly I have a husband. Though he doesn't really think I should be getting surgery, he will support me and take the kids in the beginning.