It's a lovely holiday Bex - you'll have a great time! Assuming that you will be spending the night somewhere at Gatwick I can recommend the BLOC which is nicer than the Yotel as they have windows - but if you have a shower the night before mop the floor afterwards, otherwise you'll get wet feet if you get up in the night!
There will probably be a JY rep at check-in and if you have your JY luggage labels showing clearly other travellers will probably touch base with you. Get through check-in as soon as you can and then keep an eye on the departure boards.
Have fun!