However, when the series was broadcast in Canada on the Knowledge Network, title cards were added after the fade-out which brought the viewers up to date as to what happened to Ros and her family.
Announcing that she felt as if she had served a purpose in her year and a half as Prime Minister, Ros Pritchard resigned the post and moved back with her family to Eatanswill. (What a great, disgusting name! Sorry, you lot who live there.)
Catherine Walker, who had defected from the Conservative Party to work with Ros as the Chancellor of the Exchequer, took over the leadership of the Purple Alliance and became Prime Minister in her own right. (We also learned that she never married.)
Now, this was not in the original broadcast of the series, and the usual Toobworld rule is that any events shown in the original broadcast are the official entry into the Toobworld timeline.
However, these title cards can be seen as sort of a sequel to the series; and since they don't alter anything that has come before, then I see no problem in accepting them as part of the canon.
At least this way, it gives us closure and besides - it was all in an alternate dimension anyway with no real impact on the main Toobworld. For alls I know, as Stuart Best would say, Ros Pritchard is still a supermarket manager in Eatanswill.