Be treated as an adult- yes because if you screw up they will put the majority of the blame on you which was kind of right in one sense but my sixth form neglect to take into account poor marking of exams and poor teaching. No because they care more about attendance than school which means if you are pretty ill they will pester you until you come back and will continue to pester you for the following weeks.
Work hard- yes, especially at A2 as for example with english lit coursework I chose to use my own text so I had to research the context and all the extra information.
My subjects- I didn't expect to end up disliking and even hating one of my subjects by the end of the first year and the one I am planning to take to degree level I only took as I got an A* at GCSE because it was pretty easy (religious studies) and I thought I would do english lit at uni since I was like 10 and now it's taking everything in me to keep going with it until the end of the year.
I mostly expected sixth form to be interested in me as a student rather than just a candidate number which has only been half true, I had a better relationship with my GCSE teachers who seemed to take an interest in our lives outside of school whereas my AS tutors were only interested in my grades. This was somewhat expected however it was still frustrating when in one class there was extreme favouritism shown to a few students and the rest of us were completely ignored for the majority of the year in almost every respect. It hasn't been completely awful at sixth form, I have made friends, went on a really good trip to London at AS and have enjoyed my studies so far at A2 but it hasn't been as good as I thought it would be but hey only got until June left, sixth form does go pretty quickly once you get the first few weeks/half term over.