Finally i have gotten a phone call from the armed forces recruitment centre, what to wear?

I was really excited when i finally got the phone call, as it has been months now, but i had forgotten to ask what to wear and if it matters. I will have to do an aptitude test, an interview and also a medical. All in one morning. I’m not exactly sure if i’m supposed to dress up or anything for the interview, so should i just wear my casual clothing, or a bit nicer (as in, no jeans???)

Also, it’s this coming wednesday. :P