The Student Room Group
gcses are easy compared to a levels and lots of people struggle adjusting. most will encounter at least a few poor grades at the start of their a levels, along with difficulty trying to do the work and understanding the new demands

just pay attention, keep notes and answer the questions - it'll sort itself out as long as you help yourself
You'll be absolutely fine! I remember in my first week at sixth form one of my history teachers telling our class not to worry- we are GCSE students studying a-levels, if we could already do a-levels we were two years ahead and there was no point being there and studying, we could just do the exam. Remember it's all in the process, you shouldn't start the course being able to do everything.
Just keep trying your best, asking for help when you need it, taking breaks and it will be fine :smile: