I go to Aneta's Zumba classes at Fitness First (Next to Revolution bar)in Clapham Junction. She took over the classes from Lindsay Jay when she loved to Ibiza. They are pay-as you- go classes (so you don't need a gym membership)- £8.50 a class. They are on Mon, Wed and Fri at 10.30.
They are really great classes - all abilities welcome!