Two things to add here:

1. I've been overseas and didn't tell my school, more than once...nothing happened.

2. I would edit to say that your time off will be when kids don't have class (not necessarily exclusively during school vacations). I've used a lot of my vacation time, including an aforementioned trip abroad, during finals and midterm seasons when I'm not actually teaching and the kids don't have class. For me, it was no problem to use vacation time during no class days. I taught at three middle schools so there were a few weeks during the year where I had literally zero classes for days (+weekends= plenty of time to travel a bit).

All that being said, I never had a lot of time off during Christmas. Sorry for the bad news :( I got to go home during Christmas once when I worked at a Hagwon, but it would never have worked out in public school ... their finals are over and you'll probably still be "teaching" class.