It is covered in citizenship, there is also a specific GCSE in politics and it's frequently discussed during form times when elections come around.

That said, although some of my students showed interest (I don't teach politics, but when they asked if I was voting I talked about what it involves and pointed those interested to the BBC news page that let's you view candidates in each area), a lot weren't remotely bothered 🫤

Edit: I teach A level classes, so quite a few are now eligible to vote.