Government and politics is HARD. But TOTALLY WORTH IT (I did the Edexcel course). You'll be able to expand your ability to debate over political issues, be more aware of the issues facing the UK today and understand a lot more how the government affects your life. Too bad your school cancelled French etc. because politics goes well with A level languages (I do French + loved it - doing it at uni). I really loved politics, (most) the issues are interesting/ will relate to your life in some way. Politics is NOT required to study Law.
History is also a good complement to politics, as some of the course will have recent history (between 20-30 years depends on what course/exam board you do). I've heard a lot from fellow history A level students that the history essays are insane, but if its your thing then totally go for it.
Economics is an okay choice, it's what I did at AS level then dropped afterwards. The whole PPE is still a thing.
Maths will ALWAYS be a good choice for anyone if they are capable. I detest maths and sciences because I'm absolutely useless at them so obviously I hate them, but I really wish I was good at them because they're very useful. Also so far your choices have been mainly essay based, so a subject like maths, or one of the sciences will help offset the mass of essays (I did English lit, economics, politics and French. The struggle was real). A lot of people say its hard, any A level will be hard and will blow your mind in the first couple months but we had a thing where we could switch choices within like a month if we sucked.
A subject you might want to avoid/be aware of is psychology - lots of fuss made over this subject during year 11, the actual subject is very hard and loads of case studies, but it depends on the person (I'm making no judgments here - it is probably a fab subject).
Also go through all the degrees you MIGHT be interested in doing at any uni, and then checking their absolute A level subject requirements. I know a couple of people who regret not taking a subject because they later found out it was necessary for the course they wanted to do, e.g. Biology is usually required to do dentistry.
I don't know what other options you have but there's my opinion. History + geography + politics/maths doesn't sound too bad, especially since your essay writing abilities will be literal perfection by the end of it (I jest). Humanities subjects are cool.