On my first day, we all went in and sat in the school gym for about an hour, had a talk from the heads of year about general things such as expectations, exams, how much work we should be doing and what we should be doing in our free periods. Then, the external students who were new to the school went for a tour around the school and then the rest of us just waited, until we went and joined our form groups. We had two lessons at the end of the day, and also had our school photos taken that day. I took a notepad full of paper, my pencil case and a bottle of water with me. You won't need any exercise books, and I wouldn't bother with folders until a bit later because they'll be a bother to carry and you won't really have anything to put in them to begin with.
When you do need folders though, I suggest getting a lever arch since I've found that just the ring binders fill up really quickly and can break more easily. Some people like to use plastic wallets, but I don't bother because they just break and cost extra money. You'll be wanting a hole puncher though, these are very useful and some people like to carry them around in their bags. Dividers are also really good to have. Hole reinforcer stickers are also quite good, but not necessary. You don't get your exercise books provided anymore, so need to provide your own paper. Most take in a notebook, and I personally like the Oxford Campus ones as the paper is really nice quality. A planner, if you don't have one provided by your school, is also really, really useful to have.
If possible, try to get as much work done in your free periods at school as you can. You'll have more time to relax at home and the first couple of weeks (Or even the first term) of 6th form can really tire you out. Don't let yourself fall behind, and teachers expect you to take more responsibility so if you miss a lesson, you are expected to go and get the work yourself and do it in your own time. Similarly, if a teacher isn't there your lesson might be cancelled but work will be left for you, which you are expected to do on your own for the next lesson. Remember that your teachers are there to help you as well! They are generally more than happy for you to come and talk to them during lunchtimes, after school or when they are not teaching, and try and get their emails encase you need to contact them for any help.