The Iron Lady star has been nominated for two honours at the ceremony - Best Supporting Actress for an episode of hard-hitting drama series Accused, and Best Female Performance in a Comedy for her role in Twenty Twelve.
But she is terrified her evening will end in embarrassment because the outfit she plans to wear is so close-fitting that she accidentally bared her breasts the first time she wore it.
Colman tells U.K. talk show host Graham Norton, "I tried it on and the zip split and my boob fell out. And then it took two people to get me out of it. They had to cut the zip off. It was a bit embarrassing."
The Bafta TV Awards are due to be handed out at a ceremony in London on Sunday (12May13).