Right ol' mixup here now. We buy petrol by the litre, but still drive by Miles per hour and miles per gallon. Signposts still give distances in miles (I've not seen a Km one yet). Most modern(ish) cars have digital mileometers with both available, but everyone I know still switches them to miles. Of course the old bangers that I mostly drive don't have the Km option anyway.
Most shops pretty much sell everything in Kg/gm weights and most liquids are now in litres, but there are many street markets where the Costermongers are doggedly hanging on to Pounds and ounces. They've tried to force them to change to metric by taking them to court, but I don't think there's been a successful prosecution yet. Pounds, Shillings, and pence are long gone now though, and it's only ol' duffers like me that object to paying £1.50 for a sixpenny ice cream cone.
Here in Wales all the signposts have to be bi-lingual as well. By the time you've read through the Welsh to get to the English words ... you've gorn past it anyway.
Listening to the rumblings here ... if UK do ever actually achieve Brexit (I'm not convinced I'll live to see it happen) I reckon the Taffs won't be too far behind the Jocks with our own independence referendums.