> EDIT/CORRECTION: Milk is sold in multiples of 568 mL, so while the quantities are pints, the measurement is metric.

What distinction do you intend to make by that? 1 pint is 568ml.

If you mean in labelling or something, no, they're marked 1/2/4 pints. Usually also with litre markings. You can also get metric sized bottles, i.e. on the supermarket shelf you'll often see one brand's 2 pint bottles next to another's slightly smaller 1l bottles.

The supermarket price labelling will be in £/litre, regardless of whether the bottle's pints or not, if that's what you mean?