Named driver on my dads insurance, am I covered if I have a crash?

If your name is listed on the car insurance policy, then you are covered. Whether your parents are away or not does not make any difference as long as you are a named driver. You will however need to make sure that you are driving when you have received confirmation that you have been added to your father's car insurance policy and not before that because you will be covered only when your named driver status comes into effect, that is, when you are officially listed as a named driver.