The state secondary school curriculum is based on the old grammar school curriculum and over the decades questions have been raised as to whether this really was the best or most appropriate curriculum for 90% of society. Even the old secondary modern curriculum was a further watered down grammar school curriculum with a few practical subjects - usually chiselling wood and baking cakes - thrown in. It never taught much in the way of life skills.
There are conflicts of interest over school curriculum reform. One faction of society believes that schools should focus purely on an academic education and should not be responsible for teaching anything in the way of life skills or social skills. Another faction of society is critical of traditional academic education in that it does not prepare 90% of children for the real world and believes that schools should focus more on teaching life skills instead. Even former teachers say that a traditional academic education does not benefit, or is completely wasted on, the bottom 10% of society like children from council estates in Knowsley and Hull. They would be better off mastering the basics of primary school maths and English, and learning useful life skills and how to be more self reliant.
One reason why children are home educated is because their parents believe that schools are too academic and children have a better opportunity to learn life skills and social skills outside of a school setting.
There was a British Constitution O Level about the workings of the government and politics but it sadly didn't make it into the GCSE era. I have the book by Kobrin and Scott and it is a splendidly compact and easy to understand overview of the British government. The book was published in 1979 so some things are now out of date and developments since then are not included.