With Law it doesn't matter what subjects you take, but maybe having a essay subject would help. The most useful ones could be: (You only really need 1, so do whatever you want,)
History
English Lit
Economics
Philosophy
Languages
Geograpy and so on.
You said you were thinking about taking History, Philosophy and something else. Those 2 subjects would help a lot. Both essay subjects. You said for your 3rd, it would either be French, computer science, or statistics. Honestly it wouldn't matter at all. Maybe French would link the most to Law and could be useful but it doesn't really matter. You are considering statistics, have you thought about maths? Most Unis love maths so it could help and also in case you change your mind.