Any United fans entering the away end (they would be obvious) will be ejected from the ground. I very much doubt that will happen as the game is still not all-ticket, and i haven't heard one U's fan say they'd go in the away end should they not get in on various United messageboards. I can honestly say im 99% sure the away support will not be compromised!
Also, it will not kick off at all should you win or draw. Until two weeks ago we didn't think we'd have a cat in hells chance of winning the league, in fact it looked like we could miss out on the play-offs after two straight defeats. So the fans are not really overly expectant of winning the league. Should you win it will still be a cause for celebration for United fans for two reasons - we've made the play-offs and we want to appreciate the players efforts and hard work over the season, so the last thing on our minds would be causing fights.
I guess it will be a strange game for yourselves, you can stand back, relax and watch the events unfold in an electric atmosphere of hope and expectation. It will be an interesting game, as we need to attack, attack, attack... and knowing Alty's grit and determination, it should make for a fascinating spectacle.