To be honest, 6th form is exactly the same as Year 11 stationary and bag wise. Just take whatever you want, there are no restrictions really.
When it comes to filing, some places will provide you with normal excercise books to do work in. If you don't have this system then its usually best to just use a ringbind file for each A level subject so you keep the work seperately.
File the work inside in chronological order so you can look back easily to pervious work etc.
Its important to keep everything in Unit sections too so that you know what sort of thing comes up in each Unit.
Just keep in mind at all times that you will have to revise from the folder at the end of the year so the neater and more organised the better!