Not all bread is the same. You could read the nutritional label, to figure out the net carbs in your bread. Since there are approximately 9 grams of carb per carb block, you would have to figure out what other carbs to add to your meal, to round it out.
Not sure if you are aware, or if you have read any of the books, but bread is a carb that is considered "unfavorable", or you may see it listed as "high density" on the food guide. Anyway, it is best to keep these foods to no more than 25% of your carb intake for that meal. So, if you are eating a 4 block meal plan, and if we assume that your slice of bread is 1 block, then just supplement the other 3 blocks with lower density favorable carbs.
As I said, not all bread is the same. One of the better choices would be to look for sprouted wheat bread, or "Ezekiel bread". I believe that the glycemic load of this bread is supposed to be lower.
Now, if you want some alternatives to bread, you could try a lower carb pita bread or wrap (although these are still unfavorable carb). Another idea is to wrap your turkey in a piece of romaine lettuce. You virtually would not have to even count that! Which leaves the rest of your meal wide open for other favorable carbs.