According to TVWeb.com, Sherlock will be heading to Comic-Con 2013, without Martin and Benedict.
Full article: http://www.tvweb.com/news/sherlock-heads-to-comic-con-2013-without-benedict-cumberbatch
Judging by the 'situation', I seriously doubt Martin will attend Comic-Con at all. Coz' he's like torn in 'three places' - The Desolation of Smaug, Sherlock and The World's End. And since he is not going to Comic-Con for neither The Desolation of Smaug nor Sherlock, I doubt he will go for The World's End as well. Based on the fact that up till now, The World's End's film promotion are all done by Edgar Wright, Simon Pegg and Nick Frost. No matter, let's just Keep Calm and Continue Loving Martin Freeman. Yup.