Science degrees that only require one science a level?Watch
Beyond that, I'm unsure.
But yeah as Athematica suggested, there are foundation degrees too.
I have English lit and Classics A level and an As level in Physics (which is a really bad grade). I've seen some chemistry degrees where you only need chemistry a level, so i'm hoping for something like that
I would suggest you take some time (a gap year, even) to figure out what you really want to do at university, doing an additional A Level if necessary. Given the expense of university, it's not really worth settling for whatever science subject (it's not enough to want to do 'a science') you can get into. Only do chemistry if you really want to do chemistry.