you'll need good report and essay (long & short) writing skills, be able to learn terminology/new words and hopefully have your grammar and spelling at a decent level so you don't make it hard for markers to read your stuff.
basically you need to communicate effectively, logically and succinctly and show some flair to stand out from the rest in your writing.
as you progress to higher level courses, your written language skills will need to be good as it'll be emphasised more in assignments (from experience of some friends), and exams start consisting of short/long answer questions/essays in addition to multiple choice (although i wouldn't think they'd be too harsh on english in exams due to the time pressure, as long as its decent).
report structure will be taught, although essay structure probably won't, so make sure you look through your essay structure notes from school in your second year (it'll also help you out in short answer questions). don't worry, you get a lot of practice through assignments and the more you read and practice writing, the better you get at sounding like a psychologist. plus you can go to the library/learning centre for some nice help booklet things.
hope this helps you know what's coming so you can prepare, but don't bust a nerve freaking out about it, it's not too bad.
