Education is a devolved matter in the UK, meaning that England and Wales have a different system to Scotland, Northern Ireland has a different system again, and there are some different elements in Wales from England. I will be talking about England, as it represents both my own experience and that of the majority of the population overall.
The National Curriculum for history stipulates certain broader topics that must be covered at certain "key stages" in the child's education, and gives examples of the sort of thing teachers could use to fulfil that.
One of the topics at Key Stage 3 (ages 11-13) is
ideas, political power, industry and empire: Britain, 1745-1901
With an example of
The Seven Years War and the American War of Independence.
After Key Stage 3, pupils choose a range of subjects to carry into the next two years up to the GCSE exam at 16. There are certain compulsory subjects of course but History is not one of them.
Those who do choose history will have their topics set by whichever of the several examining boards the school has chosen to use.
Of the four boards, as far as I can tell only one - Edexcelcurrently includes the American Revolution as a topic for study, as one of five possible options for teachers. I don't have any figures on how many schools use Edexcel and within that how many choose the American Revolution as a topic. Some clearly do, given that it's possible to find online discussion of the material between students. The current syllabus has been in place since 2016, and I can't find what pertained before that, so it may be that it's only been around for 5 years.
It is, in other words, perfectly possible to go through an entire British school career and never cover it at all. Anecdotally, from the numerous times this has been asked in r/askuk, that seems to be the norm.
The American Revolution simply isn't considered an important topic of study in the UK as a rule; most Brits are aware of the outline of events primarily through "cultural osmosis" - US movies, TV, stahe musicals etc. Again, anecdotally, most Brits would be hard-pressed to name the causes of the war, or give the dates, or list major battles with any confidence.
Certainly, where it is taught at school, this seems to be a relatively new development, and it is presented as one of a number of case studies illustrative of a wider topic.