Join the army, see the world.
I'm not having a go so don't get upset. But, it amazes me sometimes the number of posts we get on here asking how likely it is/what the possibility is that people will get posted next door to their mum, or boyfriend/girlfriend.
To answer your question: You will get sent where you are needed, if you are given the possibility of an option, AND there is a vacancy for your rank and experience level at that location you MIGHT be lucky and be the one whose name is picked out of the hat.
It used to be that people joined the military to get away from whence they have come, see the world, travel, have a laugh, get banged up in some foreign guardroom for nicking the national flag from the barracks, or driving through the fence of a secure airfield whilst rat arrsed.