Lee you are a young bloke so this will be your chance to prove to the Interviewing board what you are made of.
Dress as smart as you can, SWITCH YOUR MOBILE OFF, shake hands withe board members, if you don't know an answer DON'T WAFFLE, just say you don't know and move on, They will ask you at the end of the interview if you have any questions, have some ready, as an example, what will my duties be, will I be offered any training, where will I be working ? assuming it's a mobile type job, is overtime expected, i, e, wil I be expected to stay late if the job over runs, these questions might sound silly but believe me I have sat on many interviews. Have you been asked to write some sort of resume of your life experiences, you may be asked to anser a type of what if question, how would I approach a particular situation, above all be yourself, and shake hands and say thank you at the end, and good luck.