IME pré-schoolers are best served by fairly general arts and crafts classes using lots of techniques. Their motor skills are not usually developed enough to pursue a single art technique and make enough progress to keep them interested over time, with the exception perhaps of drawing and painting... And even then, it takes a really good teacher with very few children to look after.
Has anybody seen any classes for preschoolers in London? The ones I can find are either for older children or those cafes where you can paint a plate. I also saw that it's in curriculum of Waldorf school but there is nothing for after school hours. Thank you in advance.