Never been to Lydd myself, but the area referred to by LTNman would be the Biggles Bar which offers views of the apron. Apparently still closed for "refurbishment" following flooding in 2021.
This is one of the photos showing famous people there (Note that the airport was built for a superior class of traveller):
https://www.tripadvisor.co.uk/Restau...7&ff=437965020