At the theatre Vanemuine, she has played Maria Von Trapp of "The Sound of Music" (opened in 2010) and appeared in supporting roles in a popular ethno musical "Peko" (premiered in 2011 as an open air production in Värska).
On 26 May 1992 the European Academy of Music Theatre was founded in Prague's Ständetheater by the Research Institute for Music Theatre Thurnau (Germany), Vanemuine Theatre, Tartu (Estonia), Academy of Sciences, Prague (Czech Republic) and the Department for Theatre, Film and Media Studies, University of Vienna (Austria).
Sepp has appeared in stage productions at the Vanemuine theatre based on the works of: Oskar Luts, Rudyard Kipling, Juhan Liiv, Emily Brontë, George Bernard Shaw, Ole Lund Kirkegaard, Edward Albee and William Shakespeare.