You can (and should) eat carbs all day-- they are present in many of the p1 foods that you should already be eating, such as vegetables and dairy. Hopefully you haven't been avoiding those foods, thinking this is one of those low or no carb plans. Carbs are also present in fruit, which you mentioned adding for p2.
If by "carbs" you mean the p2 grain/starch options, that is up to you-- personal preference, really. You can add back whatever you miss (assuming it's a good choice, of course), or whatever you think would be the healthiest, or the easiest to buy, fix, etc.
If you're having trouble getting through your workouts, make sure you're optimizing the p1 carbs by including plenty of vegetables (including beans/legumes) and dairy. Those really help. But before or after working out is a good time for p2 carbs (grains/starches and fruit) also.
-- food lists, portion guidelines, etc.
SB since Nov '03
Goal: major weight loss (50+ lbs) & good health
Reached Jan '05!