I have a question about beating fallout 3?

May be...

When Broken Steel comes out will I be able to access it even though I didn't do a few quests?



I'm in the take it back quest.

You had better save and make a seperate game right before you beat the game or the game will end and you'll need to start a new one to play it. Considering the broken steel expansion lets you expand and keep playing the game even after you finish all the main story quests, it would be a smart choice to do something else before you beat the game and hold off until that explansion gets here but since you're on take it back (last story mission) it might be too late.

yes you will be able to access the levels but since i do not own the game i do not know how the add-on will be accessed sorry