That'd be around 57 mg caffeine. On the weak side, compared to espresso or drip coffee. You think the most common preparation is instant coffee? Kind of surprising.
In the UK? Yes. I think in the UK, most people drink most of their coffee at home rather than out at a Starbucks or similar.
Some folks have a percolator or a cafetière or a fully automatic, especially younger people, but if I were to be invited round to meet someone’s parents, I’d expect instant.
To be fair, I haven’t lived in the UK for over ten years now, I can imagine Nespresso type machines may have taken the lead.