From Longman Dictionary of Contemporary Englishsixth form collegeˈsixth form ˌcollege noun [countable] SESa type of school in Britain for students who are preparing to take A levels (=the highest level of school exams)
Examples from the Corpus
sixth form college• Tertiary colleges Tertiary colleges combine the functions of a sixth form college and a further education college.• The former Branksome Comprehensive and Darlington sixth form college pupil is now doing a postgraduate teaching course in Birmingham.• Entry to the profession may be either from school or sixth form college or from universities or polytechnics.• The sixth form college provides an excellent atmosphere and a valuable preparation for university.• These needs range across the full spectrum: from primary and secondary school to sixth form college and colleges of higher education. 