People in publishing, what do you look for in colleagues?

I’m entering my second year at University, to those who have answered questions or followed my activity from last year my first year has been a success and I’ve loved every minute.
However I feel there were something missing from my year and that was work. Good old fashioned work. I’m hoping to contact a fair few publishing houses in the district my University is based about some unpaid work experience.
My question to you publishing/editorial/writer/journalist types is how exactly can I put my best qualities across in just one letter to get something similar to an internship maybe, just some experience in the field. As you can tell from this question so far I have no idea where to start on writing this letter, I’ve been told a CV would suffice but I’m not happy with just submitting my experience in various charity shops and a bakery…somehow I feel I’ll be overlooked. I obviously have a huge passion for reading and writing and I want to express this properly. Have you or anyone you know received enquiries like mine? What type of person is likely to be taken on? How can I pinpoint my objective? Any help for writing this letter would be gratefully received.