It's funny though that 23andMe also claims I'm almost 17% British, which means I should have had an ancestor within the last 200 years who was almost 100% British (if that's even possible).

That means 17% of your DNA is similar to natives of Britain and Ireland, not necessarily that you have ancestry from there. It's kind of misleading, how these tests work. If you don't have any known ancestry from there, it's not too likely you have recent ancestry from there. 17% is about normal for a Dutch person I think. But again it really depends on your tree, I would advise you to investigate as you said!

Most Europeans show 0.2% Sub Saharan African if I’m correct

Europeans living in Europe? I don't see that much actually (and I'm on this subreddit tons)