The first part of the finale, 'The Pandorica Opens', will air on Saturday and Gillan explained that it is much more "action-packed" than the second instalment.
"Both parts are very, very different, which is cool," she told PA. "Episode 12, the first part, is kind of quite action-packed and there are a few revelations in there and things. The story is slowly starting to make more and more sense and that's quite satisfying, I think."
Gillan added that she became emotional when she read the final episode of the series.
"I cried a lot when I read it," she confessed. "So hopefully people cry when they watch it because it is sad. Yeah, it's emotional but uplifting and great."
Doctor Who continues on Saturday at 6.40pm on BBC One.