If you can, I would provide a MUCH bigger brooder before you go.
But if you can't do that, just fill the food and water and hope for the best, then check as soon as you get home.
Whenever you can manage it, giving them a bigger space will help them get used to cooler temperatures, so they can be ready to move outside sooner. When they have to stay under that heat lamp, they have to put up with being hot all the time. If they have a great big space, they can run off to play in the cool area, then come back to the heat to warm up. That helps them develop a tolerance for cooler temperatures as fast as they safely can.