Here's the deal: Yes, your metabolism affects your size, and the faster your personal motor runs, the more calories you'll burn. But the truth is, a slow metabolism isn't the real reason you're packing on pounds. You are the reason.
As a general rule, arrive at the airport no later than two hours before your domestic flight is scheduled to depart. This is somewhat later than the typical suggestion of three hours for an international flight.
Planes usually start boarding 30 minutes before departure. You need to be at the airport and standing in line for check-in two (2) full hours before your flight is scheduled to depart. If you are almost three hours from the airport it means you need to leave home before 1:00am (01:00h). If it were me, i would drive to Gatwick the day before and spend the night at an airport hotel You still have to leave the hotel before 4;00am but you can get at least some sleep - and it will be easier on the kids.