I studied at sixth form so this is only relevant if you studying A-levels, What you will need:
Pens, Pencils, Rubber, Ruler, Calculator, Coloured pens, Highlighters, Sharpeners, Lever arch folders, file dividers, hole punch, colour coded sticky notes, big pencil case, Sturdy bag, paper, academic planner.
In terms of workload, DONT WASTE YOUR FREE PERIODS, do your homework in them or prep work for class because 'doing all your homework sunday isn't enough'
it will creep up on you and you will get so stressed, besides some teachers may set homework on a Monday which is due in for Wednesday.
The five hours of extra study per A level per week, is no a joke nor an exaggeration - you need to do this from the first week. You need to start revising as soon as you start the little and often technique Is valuable here so when it gets to the real exams you aren't complete overwhelmed with trying to learn a whole specification in 8 weeks.
In terms of the social aspects you aren't the only one feeling like this, just be nice and friendly to everyone and near enough straight away you will find somebody or a friendship group to fall into.
Hope this helps:-)
P.S. sorry if this scares you but this is the harsh reality of A levels.