The only fair I do now is the Art Deco Fair at Eltham Palace. This is an English Heritage site at Eltham. Full details are on the Eltham Palace/English Heritage web site. The fair takes place in May and September.
This year the fair takes place on - 11th and 12 May 2013 and 7th and 8th September.
The entrance fee includes the Palace, the Medieval Hall and the Gardens. The fair is in the Medieval Hall.