Why don't Tom and Lily go back to the Hatchings after picking up their scooter

Tom and Lily do not want to visit the Hatchings after picking up their scooter because they are frightened as hell if Mr. Noake will find out about the sunlight only to come and then ruin their place. It was the only area where both Tom and Lily freely plays whenever they want and Mr. Noake does not want the children to be exposed.