Britney Spears left a performance of Rock of Ages in London last night with her boyfriend Jason Trawick. It seems Brit had an evening off from her Femme Fatale tour overseas and decided to take in the musical, which is becoming a big screen movie starring Tom Cruise, with her man. Britney and Jason also took time to celebrate Halloween this week with Sean Preston and Jayden James. Britney's children were in costume on Monday, and she shared a snap of their get-ups with her fans. Britney has one more day to rest before finishing up her last three UK shows, starting with a performance tomorrow in Newcastle. She's then off to Portugal, Dubai, and South America to wrap up the year.