I personally wear my Uggs all winter long with skinny jeans/jeggings/leggings, cozy sweaters, and tunics. I know a lot of people don't care for them but where I live, they are a necessity for keeping my feet warm!
I would leave this plaid shirt untucked and would probably throw a fitted cardigan like the one in the third set (maybe in black) over it as well (which you could belt if you prefer - I probably would not because I have a fear of belts. Lol.).
This is my favorite of the three looks (although I like and would wear/have worn variations of them all). The tank is so pretty and has a lot of great colors in it - red, kind of a caramel color, green, white, etc. Click HERE for the tank.