A-levels choice

I know I want to go into psychology at a degree level, most likely into development or education.
I want to do Psychology and English Literature at A-Level, however I'm struggling to decide on a third subject.
I am aware that most psychology courses want one subject like psychology, maths, biology etc so if I just take psychology is that enough?
What other subjects should I consider?

I would have a look at psychology courses and see what they want. If they only want psychology, I would pick a subject you enjoy and if you need another subject I would choose the one you are most likely to do well in, although it is still important to enjoy it.