has he worked on stage as well?
Yes, in plays like "Romeo and Juliet", "Don't Fool With Love", "Peer Gynt", "The Seagull" and others.
Michael Sheen
 After training at London's Royal Academy of Dramatic Art (RADA), he worked mainly in theatre throughout the 1990s and made notable stage appearances in "Romeo and Juliet" (1992), "Don't Fool With Love" (1993), "Peer Gynt" (1994), "The Seagull" (1995), "The Homecoming" (1997), and "Henry V" (1997).
who played tony blair in the film the queen Michael Christopher Sheen . who is this person? An actor and a political activist.
wiki:19909513
Michael Sheen [SEP] Introduction
Michael Christopher Sheen (born 5 February 1969) is a Welsh actor and political activist. After training at London's Royal Academy of Dramatic Art (RADA), he worked mainly in theatre throughout the 1990s and made notable stage appearances in "Romeo and Juliet" (1992), "Don't Fool With Love" (1993), "Peer Gynt" (1994), "The Seagull" (1995), "The Homecoming" (1997), and "Henry V" (1997). His performances in "Amadeus" at the Old Vic and "Look Back in Anger" at the National Theatre were nominated for Olivier Awards in 1998 and 1999, respectively. In 2003, he was nominated for a third Olivier Award for his performance in "Caligula" at the Donmar Warehouse.