Many universities offer competitions which can be entered for prizes, obviously, but more importantly just entering is a great way of showing your interest and commitment to a subject, esepcially ones that have a highly competitive stream of applications eg Law, Psychology, Economics, History & English. A couple have recently come through to us:
Psychology for Cambridge (choice of two essays on gender or parenting) - speak to Mrs Thomas for details)
English, History, Politics students:- Woolf Essay prize (again just for girls) - http://www.newn.cam.ac.uk/joining-newnham/undergraduate-admissions/school-liaison-initiative