Answer me please!

I just killed Saverok without doing anything from ToSC, cause i thought i should do this later, being that a "expansion"....
Now i realized the game ended after killing him...saying something like "created final save to import"
Will i be able to import my character if a keep playing/doing quests after killed him?
or should i load the game before killing him, do all that and then come back to kill him?
i fear everything i do from now on wont be able to be imported to future games...

thanks