There was a movie I saw as a child and I can not remember the name. I only remember vague pieces of it but most notably in the movie there is a young boy living in a small London apartment and is unhappy. At some point he is walking outside and is visited by an old man who turns into a strange floating golden head and speaks to this boy, The boy grabs onto his hair and travels to a far off land and has to save the world or something. I remember there being a fantasy land and a huge slide . This is all I can remember but is reminiscent of Time bandits and Baron Munchausen.

Mio in the Land of Faraway