I've been enjoying browsing around the British Film Institute site.
Lots of cycling content:
http://player.bfi.org.uk/search/?q=cycling
E.g. this CTC rail/cycle tour from 1956:
http://player.bfi.org.uk/film/watch-cyclists-special-1956/
And I remember this public information film from when it was on the telly:
http://player.bfi.org.uk/film/watch-cyclist-turning-right-1983/