Two real, long-running schools rather than a rotating menu of one-off workshops: the Escola de Teatre takes kids from 6 all the way to 18, and the table tennis section has fielded national-division teams since 1936. At €55 a trimester it is among the cheapest structured after-school options in Horta.
Horta's historic cultural club, founded in 1866, runs a theatre school for ages 6 to 18 and a table tennis school from age 10, alongside a handful of mostly adult sections (choir, photography, cinema, hiking) and school-holiday casals. Classes run in Catalan on weekday evenings and cost €55 a trimester; the office is open weekday evenings if you want to ask about the coming season in person.