I was visiting Oxford with my friend. We entered the church and bought two tickets (I guess £4 pp) to climb the tower. I was amazing on the top of the tower and you can see amazing Oxford view from there. But I feel that I have to mention that it is a bit difficult to climb the stairs as they are too narrow and steep and also it is extremely narrow around the top of the tower. So, you need to press yourself to the wall to give someone to pass by. Nevertheless, I would still reccommend this beautiful sightseeing.