All personal preference, but add me to the list of people saying get a hotel as close to Gatwick as is in budget (there's a decent range of options actually connected to the terminal - Premier Inn and Hampton by Hilton at the cheaper end but still very acceptable). It will be late, your kids will be tired, and you have to account for the possibility of a delayed arrival to make things worse. Get your head down asap and deal with the travel fresh the next day.