Indeed. I was born in 1979, and my official education was pure metric, other than literary references and the occasional unit conversion as a suitable basis for a maths question.
Imperial units are alive and well in domain-specific contexts (it's still a 30mph speed limit, or a 0.1" pin header, or a 1500mm length of 2x4), and the minds of Older People, so most of us achieved varying levels of fluency with the common ones. I seem to have been unusually resistant to measuring the height and weight of human beings in imperial. I mean, sure, 6ft means tall, but I've no idea what a stone is or what a healthy baby should weigh in pounds. I can however easily add the weight of my bike and body together to achieve something meaningful.
I'm bilingual in Fahrenheit, but only for body temperatures: Medical parents.
I spend a lot of time on the bike converting miles to kilometres and back. I measure speed in miles/hour, and UK road signs are in miles. But on bike and foot I navigate in kilometres like any right-thinking child of the 80s. I'd quite like a car SatNav to be able to do speed and distance estimates in miles, but use metres for turn prompts, but it's not really an issue in practice as 'yards' are synonymous for those purposes.
Basically it's a mess. But I think most Brits are happy to use metric when it gets vaguely technical, in a way that USAnians seem more resistant to.