SteB....there are no real 'Away' pubs around the stadium. As I said before though, you will be welcome in the Celtic pubs en route to the stadium.
Radaghast's comments were uncalled for, you are in no danger. Best bet is to spend the afternoon in the City centre which is great for pubs/restaurants etc. Couple of hours before the game, get a taxi the short distance to the 'Gallowgate'. There you will find the street leading to the stadium, full of Celtic pubs. Honestly, you will be looked after in these places and I promise you will have a great time soaking up the atmosphere before the match. From there, you can see Celtic Park which is only a 10-15min walk away.
Rovermatt, I agree Parkhead is not the best area in Glasgow....but taxis don't refuse to go there! They avoid it on match days because of the large crowds....not because there is any danger!
Those who make the journey will have a great time, and experience probably the best atmosphere you ever have!
I'll go and find a pic of the away area as promised!
Cheers