I am not a visa national. From 1st September 2007 must I always get entry clearance before coming to UK?
No. You can still apply when you arrive in the UK, but only for permission to enter as a student visitor. Student visitor is a new immigration category that was introduced on 1 September 2007. You can apply for student visitor permission only if you intend to leave the UK within six months of your arrival, and you have a place on a course that is on the Register of Education and Training Provider of Department of Innovations, Universities and Skills you will not be allowed to work and you must be able to support yourself financially without needing to work or claim welfare benefits. If you have immigration permission as a student visitor, you cannot apply in the UK to extend your stay as a student or for more time as a student visitor.