I've finished my first year of A levels. You should really be looking to study A levels you enjoy. It's a bonus if they a relevant to further study/job prospects e.g. University. I've heard that French is a hard A level to study in general, however, if you're committed to working at it, you'll do pretty well; as the same with any subject. Having a language is pretty useful and opens up more doors than you think. If you hate subjects, I don't see the point of you doing them because you'll naturally struggle and you'll probably be fed up and be reluctant to put any effort in.
It's good to be thinking of job prospects and what not now, but many people often have a change of heart after exploring their job opportunities, whether that be a change in interest or anything else. Many people walk out of Sixth Form/College/University not knowing what they really want to do. At the end of the day, if you want to be happy, go with A levels that you enjoy and you know you can do well at. I'm sure you'd rather be achieving high grades in subjects you enjoy rather than mediocre grades in subjects you're really not into. Say if you get AAA studying the subjects you enjoy, that opens a lot of doors for you in terms of Universities and what not and makes you more competitive. It's a huge risk basing your A levels off of subjects you hate and job prospects, especially ambitious ones. (being an astronautical engineer) It's all good taking those subjects if you feel you can get more out of it in the future, however, if you get mediocre grades e.g. BBC, what will you do then? Since the area of astronautical engineering is a complex one, you can expect it's only worth taking if the University specialises in it. With grades like BBC, you're unlikely to be competitive and meet entry requirements. Don't take this to heart, I'm not trying to discourage you.
It's up to you really. Also, consider the idea that your degree doesn't always need to be relevant to your job, but it's preferable. I know an older student who went to Oxford to study Philosophy. After coming out with her degree, she now works in head office sales for John Lewis earning a substantial amount of money, and she loves the job.