Don't drop french! I know it's tempting, I've thought about it many times myself. But all it takes is a little bit of confidence. Talk to your teacher, practise talking to yourself in french (I know it sounds gay)...write short notes in french. Just anything you can do to use it more.
In terms of how much work it requires to get a band 6, it depends on what your level is now. Naturally, to get a band 6 in any subject is hard, and French is no exception. Just do your best, put everything in to it. If you're not passionate about it, no matter how hard you try, it's going to make it hard for you.
Let me know if I can help
Katie xoxo