Sixth form: Grammar school or state school?

I have my heart set on studying law at Cambridge university. I am 15 and just starting year 11 with 2 A* in Maths and English already. By the end of this year, I hope to have 6 A* in total, 3 A and a B (my realistic aspirations).
I go to a brilliant school that, this year, had the best GCSE results in the county and is in the top 5% of schools, nationally. Unfortunately, the A-Level results are not coherent with the GCSE results and the head teacher has, in the past, considered getting rid of the sixth form center.
So, what do you think of grammar schools? I live about 45 minutes from a grammar school which isn't convenient, but I have to realistically weigh up what will be most beneficial and opportunistic. Apparently Cqmbridge judge undergraduate candidates by comparing the performances of the candidate to the other students in that school. How true is this?
Also if their are any Cambridge students reading this, I'd be interested in asking some questions so please leave a comment!
Any comment are much appreciated!

I'm in year 13 at a girls' grammar school. The environment is very high pressure, but it gets the results. Every year we have several people going to Oxbridge, and the support system is amazing, in terms of UCAS, teaching etc.

I would say definitely go and look at some grammar schools, and consider them, because I've never heard anything about candidates being judged based on school performance (can they even do that?) and it is in the school's interest to get all good results, so yours will be good too.

I travel 40 minutes to school and have since year 7: it isn't a problem if transport is reliable. It's quite a nice slot to 'wind down' between school and starting homework.

If high pressure environments aren't your thing, don't do it, but judging by the fact you want to do Law at Cambridge, I'd say not!

As odd as it sounds, I love working under pressure and I am accustomed to it as I often put myself under a lot of pressure when it comes to school. No one in my family has ever been to university to do such a professional degree so my education is extremely important to me.
The distance between me and the school does not hinder me, the issue is that I'd have to travel by train and due to connections, it will take about 90 minutes, (on the contrary to what you said, is probably use this time to do homework).
I will definitely be looking around at the open evenings of various grammar schools as only then will I have a greater perception of what to expect.
In the last 2 years, only 3 people from my current school have been accepted to Oxbridge.
Are you applying to Oxbridge?
Thank you fo commenting