As English

I've seen my English teacher (who teaches her yr 13s) with York Notes Advanced for Othello.

I personally would use Phillip Allan Literature A-level Guide to Othello. He's excellent because he guides to exams, exam responses, what examiners are looking for and how to improve your responses when tackling the question. Mind you, it is only for revision though.

I've used his GCSE Lit books with some of the kids I tutor at school. But have a pop into waterstones and compare the layout and stuff, and see which one you prefer.