When I found out that I was returning to Doctor Who, I was fine up until about three weeks before shooting and then I had a minor breakdown, and I thought I could never play that character again.
So I went out desperately, frantically, buying box sets and watching my own performance.
The Ood were nothing without us, just animals roaming around on the ice. That's because you can't hear them. They welcomed it. It's not as if they put up a fight.
Doctor Who - Partners in Crime + Excerpts from the script by Russell T. Davies
For the scene where the Doctor and Donna are reunited on either side of soundproof glass and thus have to mime their conversation, the script gave the lines Russell wanted Donna to act out, but he suggested Catherine Tate come up with the motions herself on the day of the shoot, so Catherine improvised her famous mime while filming.
The Doctor showed me a better way of living your life. You don't just give up. You don’t just let things happen. You make a stand. You say "no." You have the guts to do what's right when everyone else just runs away.