If I know that someone is going to be calling round for a cup of tea/coffee, then I buy cows' milk (even though it's wasteful to buy a pint just to put milk in one or two cups of tea).
The problem is what to do about people popping in unexpectedly. I tried freezing cows' milk in very small containers, so that I could thaw it in the microwave, but when it was thawed the fat stayed separate and looked off-putting. I guess that would not happen with skimmed milk, so I could freeze skimmed milk, but not everyone likes it.
Another option would be to get single-portion tubs of UHT milk, like some B&Bs have, but is UHT milk horrid?
Personally I drink oat milk, but people would not necessarily want that in their cup of tea/coffee.
What do you do, if you don't drink cows' milk?!