After being spotted dancing at a hip-hop class in London (that he was attending for fun), Tom Holland was asked to audition for the Royal Ballet School. There, director Stephen Daldry noticed the young man had the look he wanted for the title role in “Billy Elliot.”After eight auditions and 18 months of training, Holland made his acting debut in the West End production of the musical (a part he shared with three other young thesps). After “Billy,” Holland considered pursuing a career in film, but admits, “At that point, I didn’t think I had a chance.” However, when he was alerted to a call to play one of Naomi Watts and Ewan McGregor’s sons in Juan Antonio Bayona’s “The Impossible,” about a family torn apart by the Indian Ocean tsunami, he decided to give it a shot. “I thought, ‘I can’t let this slip. I’m going to go for it,’ ” Holland says of his audition, which he nailed. The emotional story, which premiered earlier this week at the Toronto film festival, has been tipped as a potential awards contender. Now 16 years old, Holland is filming Kevin Macdonald’s “How I Live Now” opposite Saoirse Ronan.