I can wholeheartedly recommend Funky Moves dance
http://funkymovesdance.com/funky-classe ... -schedule/
My older daughter has been attending the 4-6 yrs old class at La Retraite on Cavendish Rd for a year now and we talked a couple of class friends to join too and they are loving it! You can call and check if they have classes for 13 yrs old too.
It is mixed boys and girls and wonderfully action packed 45 minutes, they are at the studio on their own (parents can wait outside or in the school gardens).
And you can always book a taster class free of charge or try a holiday class during half term.
*no association with the funky moves dance company, just a happy customer!