Although it was never made explicit—which was probably meant in keeping with the fact that it was never made explicit who Claire Bloom's character was in The End Of Time—I think the suggestion in "Hell Bent" was that the woman in the barn was actually supposed to be the same character, believe it or not! They are both credited simply as "The Woman" and the same theme is played over the scenes where each exchanges long, meaningful looks with the Doctor for the first time.That reminds me of another dropped thread: what about the ashamed woman hiding her face, who we assumed was the Doctor's Mother?
I do not think she was the Doctor's actual mother (who was human damn it
) even though that's who RTD thought of her as and told Claire Bloom she was playing. He did also say that he left her identity deliberately ambiguous so as to allow the audience to speculate on it for themselves. At this point I'd say she was an adoptive mother figure to him as a child.