We flew to London with DD when she was 22 months - we were lucky as every flight we got on the staff automatically allocated us another seat even though we hadn't paid for it. I think as long as there is room on the flight they are normally pretty understanding with little one's. We also always got lots of food for her even though we hadn't paid for her seat.

We took lots of small toys/games/crayons etc, but the thing that saved the day was our Ipad with DD's own headphones. Prior to leaving I downloaded TV episodes and apps that she just loved. Really was worth the investment as she was so well behaved.

Good luck with your trip! I hope you end up with nice staff like we did who give you that extra seat.

Janie xxx