Clubs which offer opportunities for younger players are listed on the web sites of:
The Hertfordshire Schools Badminton Association
The Middlesex County Badminton Association
London Badminton Academy (listed on the Badminton clubs page of this site) welcomes younger player from age 6. Further information is available on the Academy's web site:
The Badminton England Discover Badminton site will help you find local badminton clubs and other opportunities for playing badminton (click on the arrow next to Book Online to see a list of the different opportunities).