Gresham College's free online lectures may be a useful resource for sixth form and college students for career choices, for university statements, for extended project qualifications, and generally for academic stretch.
The lectures are usually 45 minutes to an hour long, and range across the arts and sciences. Professors include Chief Medical Officer Chris Whitty, Historian Richard J Evans, Classics Professor Edith Hall, and Astronomy Professor Katherine Blundell; and you can read more about the wide range of subjects they cover online here.
Gresham College is a charity and has been running free public lectures since 1597.