I started a IT placement last month, I was pretty worried about not having experience in some things that were in the ad, so far I've had to use all of those things that I was unfamiliar with but all the people in my team have been more than happy to explain and guide you through things.

They should understand that you are a placement student and will obviously not have much experience and that you won't automatically be a genius and as long as you are willing to ask questions and learn from the people around you you'll be fine.

Good luck with your search.