Prepare for the core questions and provide good examples to support your answers. Use "I" not "we" when providing your examples, you need to sell yourself. You have no doubt been working towards this for a number of years, and have the knowledge and skills necessary it is just a case of communicating what you know. Try no to be to worried, which is sometimes easier said than done. In my case the panel really put me at ease and I came out having enjoyed the interview, though still with uncertainty as to the outcome. The relief when you get a positive outcome is worth all the effort you have put in to get to this stage.