We found the following Judo classes around WD18

Batchwood Sports Club, Batchwood Drive, St Albans AL3 5XA

27-53 Elfrida Rd, Watford WD18 0AT

iruka Judo - Watford based Judo Club, training on Tues and Thurs. Elfrida Road. Field Junior school.

Community First, 245 Rectory Park Ave, Northolt UB5 6SD

West Acton Community Centre, Churchill Gardens, London W3 0JN

Sandringham School, The Ridgeway, St Albans AL4 9NX

Combat Gosling Sports Park, Stanborough Rd, Welwyn Garden City AL8 6XE

Briars Ln, RoeHill Hall, Hatfield AL10 8EY

242 Acklam Rd, London W10 5JJ

58 Claremont Rd, London NW2 1BU