Hey there, I was exactly in the same position as you a year ago.
I retook the year because it is not impossible, but very difficult to get grades when retaking the same subjects in the same year. You'd often get the same grade or only get an E at best usually. Don't let that put you off though!
Needless to say, I got my results yesterday and I got an C in History but a U in Economics again. I had to change it for an extra BTEC so it's two BTECs and an A level in History.
It's not the end of the world, try contacting other sixth forms near by. Bombard them with emails if they are still doing enrolments, it will usually take place during next week when the Year 11's go to collect their GCSE's. The earlier that is done, the better.
Good luck and we should hear about how you are getting on very soon!