I would call your local WW center (or whoever runs your local WW meetings) and ask - they may run specific Mom and Me meetings. I know that when I've gone to Friday morning meetings, there is always a new mother with her infant and a couple of older kids. Also, my leader had to bring her 3 kids one week, because she had no one to watch them! I know that my center is ok with it, as long as the children are quiet. (I would assume this rule is for the older children) Also, you may want to sit close to the door, in case you have to make an early departure.
Good luck! Going to WW meetings was one of the best things I've ever done for myself.