I must say you are incredible for a 14 year old, really, and are almost making me feel I shouldn't be doing law as I don't even know enough about the conflict in Southern Lebanon really to argue with you!
I understand a little of how you feel though, as I used to act a little more grown up than my peers (although, I must say, was nowhere near as prepared as you are!). It has its upsides and its downsides. Once you get people to get over the 'oh my god, you're only 14' stage, they will take you seriously and help you get where you want to be. This includes work experience, although I'd wait a couple of years for that, as most law related work needs you to be over 16. In terms of your A-levels, keep in mind your plans now, but don't be afraid to change your mind. You may change direction entirely over the next couple of years, and that's OK. At my school most people spent the first few weeks of year 10 changing GCSE courses, so I can't imagine ANYONE was sure what A-levels they wanted to do!
The downside is that most people really aren't prepared to deal with a 14 year old who is so much more prepared than the average 18 year old! You will find you have to wait a while before you really are treated like an adult who fully understands this stuff, because most people will just assume you can't. The point is, you are still just a teenager, and, while you say the other people your age can't argue a point, the fact of the matter is that they're not expected to. You just have to accept that they aren't as advanced as you are, but that doesn't mean they won't come into their own over the next few years, possibly even through being friends with someone as intelligent as you. Don't look on it as a separating factor. Just bear in mind that within law and the police you are expected to be able to deal with all sorts of people, so separating yourself from them by unnecessarily advancing your knowledge of the law may only turn out to be a disadvantage one day, when others may be able to deal with both. I know you don't want to think of yourself as a 'normal child', but maybe it would be better to allow some of those childlike tendancies to come out occassionally?
The point is, everyone grows up differently, and I can't tell you what is right/wrong. To take my example, I worked hard at school when I was quite young, not knowing any different. When I reached year 9, I got fed up of it and gave myself a bit of a break. I still tried fairly hard in the subjects I cared about, but I dossed a lot in subjects I didn't, put off homework, and failed a few tests here and there. It didn't stop me getting 4A*s, 6As and 2Bs at GCSE (not an outstanding result, but pretty damn good)! Only in year 11 did I started to take law (slightly) seriously. I got a day's work experience in a legal department of a big firm, but I didn't worry too much about doing much else, because, to be honest, this was far more than a lot of people had done by that age. I really worked hard again when it came to my A-levels, and it wasn't easy balancing school, work and improving my application for law, but I managed it! I'm not saying don't try hard, as getting ahead can be a big advantage, but I'm merely pointing out that you can let yourself go and pick yourself back up! Most people weren't even as prepared as I was!
In terms of A-levels, I would recommend against A-level law, just because I've heard so much against it. But I don't know what it is actually like, so don't take my word on it - if you're concerned look on university admissions pages closer to the time (it may all change by the time you get there, so our advice might be rubbish!). But, I'd say, if you are already more advanced than A-level law, I'd imagine you'd be better off proving and improving your competence in something else at A-level, and using what you know about law for interviews and for when you get to uni.
Again, in terms of universities, you'd be better looking at league tables in a few years, visiting some when you've got a better idea of what you want out of them, and deciding then. A lot may change between now and then, and you might want to pick a uni close to/away from home accordingly. Ideally you'll want to have a shortlist you're a little interested in by spring year 12, visit them, get their prospectuses, etc. in the summer, and pick your 6 favourites by the beginning of year 13 to get your application in early, but you can do this earlier if you wish. (I visited both Oxford and Cambridge in the summer after year 11 to pick between them, but that's me being over-prepared!)
When you get to sixth-form, which is still a long way away, I'd recommend you get some work experience (I spent a week in a solicitor's and a week in the local council's legal department) and, if you can, go on the Cambridge Sixth-Form Law Conference and the Oxford Law Open Day in year 12 (look into this right at the beginning of the year, as you need to book through school). Both are really worthwhile - the Cambridge one costs money, but is really worth it, being a four-day conference, where you stay in a college. There are other privately-run ones which are pretty good, but tend to cost more. If you're interested in criminal law, the Nottingham 'Workshop' Criminal Law conference may be worthwhile. Anyway, these may change by the time you're old enough, so look into them closer to the time, but I found that it's difficult to know that these things are happening unless you are told well in advance, so I thought I'd help you get ahead of the game!
Anyway, contradictory advice there, but it boils down to:
1) Don't worry too much right now, and keep on enjoying being 14
BUT
2) Being prepared is not a problem, as you will be ready to do what you need to when you get to each stage, so keep up with what's going on, and keep your interest going. Just don't let it become too important!
It's a balance we all have to get right! I hope this helps you!