They don’t celebrate Christmas, but your school may give you one day off. But in January/ February time there is a 2 week holiday (depending on when the dates fall), which is a good time to do a bit of traveling around Turkey. Although it is rainy during this time, it’s a great opportunity to explore - as there aren’t many tourist about. I suggest going to Pamukkale, you can get some great photos as there isn’t anyone there. I heard in the summer time it’s like an ants nest, with thousands of people crawling all over it.
Turkish people are very friendly and will invite you out, you will never be lonely in Turkey. I used to socialize with my fellow co workers, they love to dance and go out drinking. As a Muslim country, you would expect the women to cover themselves from head to foot - wrong! Most of the females dressed in short skirts and tight tops (in the cities that is). The men looked, and dressed, like male models. Istanbul is very cosmopolitan.
In some cities it is very dangerous to go out in the night in some areas, so make sure you get the low down before you head off for a night out. I was told of a gang problem in Istanbul, especially the side streets of the Taxim area at night. So, stick to the well lit areas, but that goes for any city in the world too. I would always go out with Turkish people, which made me feel safe. Some times when entering a club you will get searched or even go through a metal detector, but this is a good sign at least you know there won’t be any trouble there. There are many clubs where you can belly dance the night away!