I've just finished Year 13 after having taken French as an A Level (never got to take the exam though, obvs!) and I really enjoyed the course. I highly recommend that you keep up with your French over the holidays as I didn't and on the 1st day of Year 12 I realised that I had forgotten some of the basics, so definitely revise some vocab and tenses. My exam board was Eduqas and we studied topics such as music, politics (specifically the National Front/rise of the far-right as well as issues surrounding immigration and multiculturalism), education and the world of work (these topics were covered in my GCSE course too so I knew some of the vocab already), and the changing French society which included stuff like same-sex marriage and single-parent families. I should also mention that your studies will probably not just be about France but also other French-speaking countries and you'll probably have to do research about them. I think with all exam boards you have to study a book and a film. You must write essays about these in a similar style to how you do essays in English - lots of analysis and a similar structure too. The prospect of reading a book in French was quite daunting but at my school the book we did was quite short and our teacher read it with us and it wasn't too hard and I ended up really liking it.
My least favourite thing was the speaking as for your exam you've got to do an Independent Research Project which must be related to France/a Francophone country. You'll need to do a short presentation about your chosen topic and then the examiner will ask you questions about it so make sure you do lots of research! I recommend thinking of questions that you may be asked and then writing model answers for them to revise from. Unfortunately you cannot ask your teachers to help you with any aspect of this! What helped me was writing out bullet points and memorising the key things. If you need any statistics and can't remember for the exam, you can make them up as long as they are believable!
I'd recommend familiarising yourself with France's culture and history (especially the Second World War) and keep up with current events. Also keep revising your tenses and be prepared to learn many more at A Level! You can also try reading some French children's books - I read 'Le Petit Prince' in my free time and I did learn some new words and I also found it very satisfying when could read it without needing to look a lot of stuff up. My teacher also gave us some French Disney books like Winnie the Pooh and Aladdin and I found those very helpful and fun too. Watch some French films too with English subtitles! I recommend 'Les Choristes' (also happened to be the film I studied), and 'A la folie... pas du tout'. I really enjoyed my course and I am hoping do French for my degree! It can be hard at times just like any A Level but it's lots of fun and very useful.