Is this only going to apply to UK hosted pr0n sites or worldwide?
Define "pr0n" in that worldwide context. No doubt some MPs will be thinking along the lines of the USA school that sacked a teacher recently - for letting an 11 year olds art class see pictures of famous works of art that contained nudity.
Last year my neighbours' son's UK school set their 7 year olds a homework project to research sculpture. His parents asked for him to borrow a reference book on the history of the subject. It probably included pictures of ancient fertility figures, a "David", and various other famous sculptures.