Well, if you're going to a chain, chances are they have nutrition information available. So look on the company website or another site that provides nutrition info for fast food. For example, Dotties Weight Loss Zone has a fairly comprehensive restaurant nutrition database:
http://www.dwlz.com/restaurants.html
What I wouldn't do is go into a situation like this with no plan. Otherwise, temptation will lead you into making poorer choices than you might have otherwise.
If you go out and you're not sure where you'll be headed, you might want to keep a list of a few healthy items at the places you're likely to end up with you. That way, wherever you land, you can still know what you're getting and find the healthier options.