Travel to Children's Railway from Central Budapest

GoodBottleOfWine

When we visit Budapest later in the month can anyone advise me of the best way to travel from Central Budapest (opera House Area)bus route number cost how long it takes . Any advise will be most helpful as we like to plan in advance. Thank you 

user1977

Google Maps result here: https://maps.app.goo.gl/dtXcZnuvH6iH4wabA

Looks easy enough, there's a tram terminus next to the railway.