Take a plastic baggie and put your sandwiches in it to have while you wait for immigration or bags! They aren't going to let you have your tray down during approach and landing and I would guess you don't want sandwiches on your lap! You say "we" so I think you are travelling with someone? Maybe they could get the sandwiches while you continue sleeping? Does 30 minutes more of what is bound to be disturbed sleep with cabin lights on etc. really help? They will wake you at least 20 minutes out (or they should) so that your seat is upright, etc.