Provide them with an actual sex education?
I don't mean talking about how the penis works and how to wrap a condom on a cucumber, because I think the UK does that already.
I mean actually talking about how to have great sex, what works, how to please a partner, etc. Feel free to have a final where students have to review some porn and point out the parts that doesn't work in reality.
Of course that would horrify parents and teachers, but the reality in 2019 is that you can no longer _not_ talk about the subject, you can only leave the discussion up to the porn producers and mind geeks search engines or get into the fray yourself.