Battery is drained and I cannot get into the car?

Hello, I have a mini and the car battery has drained on it. I've tried using the key out of the key fob but that's also not working. I don't have money for a mechanic and was wondering if I could get in there another way. I have brought a charger to charge the battery but obviously I can't get into it. I did learn that I could charge it through a wire in the fog light but also learned I could short the whole car so I'm not really sure on what else I can do. The boot doesn't have a key lock so I can't get into through the back and I really don't want to break a window.