Beef Jerky, Peanut Butter and bread, cans of tuna... You can take this stuff with you!
There are plenty of other things you can take with you as well. As for training you can miss a week. While not ideal, personally Id go hard on the weekend before and when you return so its about 5 days that youre not training
Edit: We sometimes get sick during cycles (I think I have a flu atm, which means its difficult to eat, and training is out of question. Just keeping up fluids, bed rest.. been about 3 days and Im feeling much better). So you should be ok. Sometimes life gets in the way of the best laid plans.