I drink copious (in my humble opinion) amounts of tea. Like 400 ml for breakfast. And I take milk in it.
Milk contains lactose, which will be the subject of this my return to posting about chemicals and engineering (in varying proportions) and the bane of many a stomachs. The image depicts beta-D-lactose, where the beta stands for the stereochemistry around the glycosidic bond that joins the two constituent sugars, glucose and galactose. Glucose is sweet and lactose is not. Milk contains around 4 % lactose which can be removed enzymatically by splitting the molecule or via a chromatographic method. The enzyme leaves glucose and galactose in the milk, and in principle it tastes sweeter than normal, lactose-y milk. In theory this also means that lactose free milk goes bad faster.
Practically, though, I’ve seen little or no difference. They both run out at the worst time.