At my access course interview we had a comprehension test, there was a short piece of writing about social media and we had to write an essay (I think it was around 500 words) about what we thought the authors view of social media was. After that we also had a choice of 5-6 topics to write an essay about (500-750 words I think).
Other comprehension tests I've heard of are where you get a short piece of writing and then multi choice questions about the extract e.g in the second paragraph is the author referring to a... b... c... or d.... Examples are available online to use for practice.
I hope this helps a bit.
If you don't mind me asking, do you meet the requirements to apply for nursing, as you said you were going apply this year in your post or do you need to do an access course in order to apply?