Jinkster- I'm assuming you have a cityjet assessment, hence the requirement.
Believe me if this is the case, I would strongly recommend spending a few days in dublin with a few hours on the sim beforehand and then the rest of the time in the cardboard mock ups (free!). Simtech\Parc should also be able to provide you with the relevant material whilst there.
Good luck
re- cpat, there is no way of re-using an unlock code as a different installation code is generated each time the software is downloaded or copied.