Nice one. I got a Bolt job from zone 18 today immediately after dropping at T2 so took a chance on it. Only difference with not having the permit is that you have to press the button for a ticket to get in and use the ticket to get out... Fee is the same i.e. €3.
However, Bolt doesn't separate the car park fee from the fare the way it does for tolls so you end up paying commission on the €3 you add to the fare hence you need to add an extra 40c (it only accepts fares in 20c increments) to cover yourself.