Instant coffee with only milk? I like milk. So I thought of doing milk with instant coffee. I mean, I have coffee here but it says I should use water. I always use it with water and put a little bit milk.

Can I also use only milk without any water?
Milk is mostly water.  Instant coffee will dissolve just fine in milk or even cream.

Of course, flavour-wise it's going to be more like a weak latte than coffee.  That's essentially what a latte is - coffee and milk.