Listen, it’s very simple: In Britain we use the metric system, except for beer and milk, which come in pints. But not plant milk — that comes in litres.
Oh, and distances are in miles. But only if they’re too far to walk — if you can walk it it’s in metres. If you’re driving then your fuel efficiency is in miles-per-gallon, but petrol is sold in litres.
Oh, and your height is in feet and inches. If you don’t care much about your weight it’s in stone (but not pounds — no-one can remember how many pounds are in a stone and it’s hard to read the little tick marks on analogue scales). If you do care about your weight then your digital scales tell you it in kilograms.
Oh, and if there’s a heatwave then tabloids will forecast a “100°F scorcher”. But if it’s cold then it’s an “arctic blast” with “widespread temperatures below 0°C”.
I hope this clears things up.