OP, you seem to be getting a tad confused in the mix of conflicting information, so I'll try and tidy it up for you:
1) IF, and only IF, your first language is French, should you not study French to A-Level(though another foreign language would be good). If French is NOT your first language, disregard this and carry on.
2) English Literature is respected more by top universities than English Language. There is an A-level in combined English Literature and Language, which is acceptable as well, however, it isn't a good idea to do just English Language.
3) Self-study is only an option. I personally think the conventional ideas such as teaching are overrated; I get high A grades studying by myself, but I do Sciences, not Arts/Humanities. Private tuition is overrated as well. The grades are inflated by the wealthy, educated backgrounds the pupils come from.
Also, please, please examine whether your aspirations match your realistic prospects. Law schools are competitive, especially one's such as Oxford. Are you truly confident in your ability to study Law?
I'm always apprehensive of saying things like this. It sounds like I'm trying to dump on people's dreams, but on the other hand, I've seen and am currently seeing people waste years of their life chasing something which so obviously isn't going to happen. Someone in my Chemistry & Physics classes was a C grade at best in GCSE's, is E grade at best in A-levels, yet wants to go on to study engineering. His prospects are bleak, and it's sad to see him wasting so much of his time and energy without a single teacher telling him the truth.