You have to complete 3 A levels. If you are at college/sixth form they will require you to do 3 A levels and you won't be able to get into a lot of unis without 3. You could redo your 1st year, if your college/sixth form allows but normally they would want you to have a different A level combo and a reason as to why you are redoing your 1st year (is my understanding don't quote me on this). I would go and ask your tutor about it and see what they say.
To answer your question: Most prefer you to have maths or a science but if you don't mind limiting your options a bit, then you don't have to have maths.