Hey.
I can totally relate to you. I've applied to do law at Birmingham University (firm) and they want AAA, however I feel incredibly opposed about going to my insurance choice which is Nottingham Trent. My reasons for this is that I didn't get a chance to see the university (my fault I know, but I had to choose between seeing Bournemouth or Nottingham trent, and I thought as bournemouth is further away it'd be better. I actually didn't like bournemouth very much so I am gutted!)
I have friends who do law at nottingham trent and they love it, but I personally just need to see it for myself. Also I have totally fallen in love with my firm choice, I love the city of Birmingham, the university and the course they offer. I haven't felt that way with any other uni, and a law degree from birmingham is regarded highly than one from nottingham trent.
I've re-sat my whole AS law course in January and loads of biology exams to try and get those three A's.
Basically, if you don't get into UCL, just consider your options and at the end of the day, you can resit your exams and do any additional work experience or other things to put on your personal statement to apply for next year.
Don't worry.