native english teacher for children (Madrid- Retiro)

I am looking for a native English teacher for my 6 and 4 year old kids, 2 hours in a week. Mondays and Wednesdays from 18h to 19h more and less We are more interested in them doing fun activities rather than proper structured English lessons and are therefore looking for 
someone who gets on well with the children and is able to make them play and involve them in English conversation. In madrid (Retiro)