No, fruit smoothies are not good.
Fruit juice is terribly calorie dense. Most fruit is also far too many relatively empty calories and fructose - yes, I said empty (you get some vitamin C, fibre, water, and sugar generally speaking, that's about it. Compare this to any vegetable and you will see that eating an apple/orange/kiwi etc is not worth it).
Strawberries are probably your best bet, being so low on calories. Strawberries and blueberries are high in antioxidants.
The best time to drink skim milk during a cut if at all is PWO, where milks high insulin index is a plus. Many people don't drink milk during a cutter. There are however scientific studies suggesting dairy aids weight loss, but query whether this can be replicated without the milk carbs by simply calcium supps + casein shakes. There are question marks I think about how fattening galactase (i.e., can it be stored in muscle glycogen, or does it behave like fructose)