Both Jenna and Time Lord Matt Smith said they tried to avoid going online too much and did not use Twitter.
Matt said: “I spend so much time on my phone and I find the idea that you communicate your life via Twitter quite peculiar so it doesn’t really interest me. “It is not up my street, I am not on Facebook either, I just cant be bothered.”
Jenna added: “I am the same it is just about trying to keep off the internet really.”
PSA: neither Matt Smith nor Jenna Coleman are on Twitter
When they do post they post through the Doctor Who (Public Service) Blog, Doctor Who Facebook Page, and this here Doctor Who Tumblr.