Hi!
I finished A2 German with an A* in June and I'm currently studying German at university, so I hope I can help a little bit
Like with most subjects, the gap between GCSE and A-level German is usually pretty big. Quite a lot of people in my French and German classes dropped out within the first month.
It all depends on the exam board your school is with regarding the format of the exams. I was on Edexcel, and we had a 2 and a half hour combined paper of reading, writing and listening. For this, no matter which exam board, you
must do extra reading and watch the news regularly to keep up your aural skills. I made this mistake in AS, and completely freaked out in the exam. Not many people get an A at AS purely because the exam is such a shock.
The language becomes very complex. You learn that some of what you were taught at GCSE was a complete lie in terms of grammar. You learn new tenses and new structures and you have to start applying this in your writing and spontaneous speech. With the speaking exam on Edexcel, I had a 25 minute exam. We had to pick one of four broad topics and were given a stimulus card with a short text containing a subtopic of the main topic (e.g. I chose Youth Culture and my stimulus card was on computers/computer games). You are then given about 10 minutes to anticipate which questions the teacher will ask you (the teachers are already given a list by the exam board). After this, the exam is about 15 minutes. The teacher will ask the 4 questions related to the stimulus and then you move away to the general topic... so this is
completely spontaneous. A-level languages are different from GCSE in that the speaking exam is not an 'interview' as it were... they're more a discussion.
Other exam boards differ slightly.. but the main things to remember are:
-Grammar matters more than ever
-You need to have opinions on general topics - this can help with the speaking exam
-It's useful to read German newspapers and listen to German news shows on a regular basis
-Learning things by heart will not get you a high grade
-Spontaneity is key
Hope this helps!!