I haven't seen a sugar-free variety in UK supermarkets. Standard Cheerios have always been sweet. I would call the "sweet" varieties things like Honeynut which have 22.4g of sugar per 100g.
The "low sugar Vanilla O's" sound ridiculous but contain comparable sugar to base Cheerios.† Presumably they have more vanilla flavoring.
† Which is to say, there's still a bit of added sugar, but not much, just like in the base Cheerios. (The rolled oats have no added sugar. The difference between "1g" of sugar in 40g of American rolled oats and "1.1g" in 100g of British rolled oats must be down to either different oats or rounding errors.)
I feel like the constant addition of relatively small amounts of sugar to random foods that aren't even supposed to be sweet might be a bigger issue than the inclusion of big heaps of sugar in foods that are supposed to be sweet. It's difficult to find beef jerky that is less than 10% sugar by weight. Rice Krispies are also 10% sugar by weight. There's no good reason for this.
