In reply to iusedtoclimb:
Crikey - good luck. You can get a train / tram ticket from where you live to the stadium, but whenever I have been in town when Utd or City are playing the trams are absolutely rammed. Similarly, the motorways around Manch are completely rammed on match days so goodness only knows what the roads in the area will be like.
All I can think is to prepare for the worst. I am not sure I would want to park on the street around the city ground. It isn't what you might call an affluent area.
Good luck!