See if you can host something like a bake sale or something along those lines to raise money for your trip. I mean, it might be difficult to get enough money to take the trip. But, you can combine your own money aside with your parents and see if you still have enough for the trip and your christmas. I don't exactly know how much £1200 is compared to U.S. dollars, but I'd assume it's not an incredible difference. Also, if you have some wealthy relatives perhaps, you could always beg them for money. Also, maybe mow your neighbors' lawns, do something they would pay you some nice money for.