I was just watching Loose Women (yeah I know), they had some figure saying that 44% of girls didn't know what was happening when they started their periods and discussing whether it should be taught in schools.
I went to school in the 80s-90s, and I can clearly remember in primary school doing sex ed. It was one afternoon every week and was all about puberty. They separated boys and girls to prevent the silly giggles and we learnt about everything from periods to body hair to boys voices breaking and wet dreams. We had the opportunity to ask any questions, we did little true or false quizzes and we were given sanitary products.
Later on in secondary school, despite going to an all girls school, we did more sex ed which this time was around safe sex, pregnancy, contraception and stds.
I just always presumed that this was the norm and that it still took place now.