Dropping someone off at UK airports can add up—on average it costs about £6.51,...

https://dlf-ne.org/is-paying-two-barrier-fees-ever-the-right-move-at-uk-airports/

Dropping someone off at UK airports can add up—on average it costs about £6.51, but places like Gatwick hit £10. Heathrow’s around £7, and remember, pick-up fees can differ too