The world actually ended in the hands of The Master or The Daleks and it turned out that many events leading up to hundreds and millions of years ago lead up to this event and they spend the next series going back and changing the future.

It probably sounds naff but at least it would change from the natural 2 part finale where the end of the first part the world gets over run by aliens or whatever and in the last 15minutes of part 2 they just managed to prevent it by some bizarre coincedence. Just what if at the end of a series The Doctor was to late.

oh and i have not seen any episodes prior to Christopher Ecclestone's doctor so this may have been done before

I don't recall that happening exactly as the Doctor has always tried to avoid changing events. I guess it would depend on whether the Master or Daleks changing the past was always meant to happen. That could be a fixed event in itself.

To be honest, though it is an interesting idea, I would prefer the Earth not to be in peril for once. I think I've seen too much of that. The Doctor travels the universe, so let's see more of it please Mr. Moffat.

That scenario is one way the Time War could have happened.
Although it's never been stated what exactly the TW was, it could be assumed to be like this:

Daleks travel back and alter history to give themselves an advantage.
TimeLords go back a little further to prevent that adjustment.
Daleks go back and alter that adjustment.
TimeLords go back and change that.
And so on...

Sort of like the end of Bill and Ted: "Then we'll go back and fix an anvil to the rafters, right above you."
"Then I'll go back and move it slightly."