Some useful links:

FIDE: World Chess Federation
English Chess Federation
ECF Grading Database
Southern Counties Chess Union
Surrey County Chess Association
London Chess League
Thames Valley Chess League

Chess24: watch and play online chess
ChessBase: latest chess news & software world’s no. 1 chess site. Online play, lessons, quizzes etc. top chess website for children – and their teachers/parents

London Chess Centre, online shop & CHESS magazine
World Chess Championship 2018: Magnus Carlsen v Fabiano Caruana in London.
London Chess Classic 2018: world stars playing in London + tournaments for all
Chess in Schools and Communities
Delancey UK Schools Chess Challenge

Richmond Junior Chess Club
chessKIDS academy: online interactive chess course for children
Minichess UK: teaching chess to young children using age-appropriate games and puzzles using subsets of the chess rules and pieces
Chess for Heroes: coaching materials for parents teaching their children at home

These last three sites are run by Richmond & Twickenham Club President Richard James: please contact him for further information on chess for children.