Just a slight but important correction, they will only use skimmed milk if you ask them to. I used to work at Starbucks and for all hot drinks apart from a flat white, they always use semi-skimmed milk.
Just a little advice netty, Starbucks can easily be enjoyed using little syns. There's 340ml in a tall cup, so that's your HE A for the day if you use skimmed milk. If you have a latte like this without any whipped cream and with a sugar free syrup (they do caramel, vanilla and hazelnut), you'd get a syn free treat for the day. I do this regularly with hot chocolate, which works out at 3 syns for the chocolate syrup they use, and it's never affected my losses