IMO you should just use a variation of you home tactic when playing away.
Try and keep the same shape, but just alter farrows/barrows, Mentality, DL, CF etc to make you more defensive and solid.
The main thing you should look at when facing the opposition is the odds of winning not so much wether you are home or away.
For example: playing Man U at home it would be an even game (depending on form and league position) so alter your tactic to suit.
On the other hand you could be playing Derby away and be massive favourites to win so you wouldn't play your default away tactic you would play your home tactic and probally come away with a comprehensive win.
You should never overlook the odds before a game as it gives a good indication of the outcome.
Hope that helps.