UK maths teaching is fairly terrible. Not only do they start later, it's almost never taught meaningfully, instead relying on memorising rote formulae. I grew up hating maths, it wasn't until YouTube came along and the sheer amount of _good_ maths content on there that I started to 'get' the bits I just never understood as a teenager. Most of my friends will still say things like 'I just don't get algebra / I don't do maths', and I put this down to how it is taught, which isn't very well.
The main issue is the curriculum and exams emphasize this kind of rote learning (across the board, not just in maths: one stupid reason for this is many of the markers for the exams don't actually have any qualifications in the subject they're marking and need to be able to just pattern-match off a mark sheet). And because teachers and schools are judged so heavily on exam results, they are not just incentivised but basically forced to 'teach the test' as opposed to trying to get the students to actually learn anything, even when they are otherwise motivated and capable of doing so.
I went to a quite high-performing school, and it wasn't unusual to have a year be 60% 'getting through the curriculum', 20% 'teaching interesting things about the subject', 20% 'exam prep', and that 20% in the middle only existed because of the extreme priviledge of both students and teachers good enough to keep up with that pace and a level of enthusiasm for the subject which allowed for teaching stuff 'not on the test'.
Ah that is lame that you had to go through that. I remember in my calc class the teacher said we would spend no time learning for the government standardized test. If you can't already pass it you have no business being in the class.
Yeah, with different tests it may be different. But in the UK the government pushes for 'more challenging tests', which means more stuff to memorise, a lot of the stuff is very specific (in science GCSE and A-levels there's specific phrases you need to use to get marks. Accurate descriptions which don't include those key phrases don't get marks), and there's a lot riding on getting near perfect marks. Someone who has a good memory and a few months to prepare and an expert on the topic with years of experience (but no specific preparation) have about the same chance with these exams.
Has it changed since the 1960s? Maths where I grew (Swindon, Wilts., ) up was pretty good and from first form (age 11, 1966) on used the SMP course where there really wasn't any memorization of rote formulae: https://en.wikipedia.org/wiki/School_Mathematics_Project
The earliest I was introduced to discrete maths like this was my first year of uni -- that course looks really interesting. I know they teach CS at high school now
Not sure about youtube, but for the right age kid, maybe late-elementary to early high school, there's a weekly "Joyful math jamboree" online. The web page for it is not updated very often, but the registration form still works.
There's also the Julia Robinson Math Festival that's supposed to be good but I don't have first-hand experience.
Ideally, a Math Circle would could be good for some kids if your area supports one.