I have experience of training students for examinations with all the major British Exam Boards, as well as the International Baccalaureate organisation. I have also tutored Common Entrance candidates.
Not all my students are training for exams, however! Some (particularly adults) are simply learning for the fun of it!
Here are some useful websites for those who are preparing for exams:
(AQA examining board).
(OCR examining board).
(Edexcel examining board).
(International Baccalaureate Organisation).