Okay, on to the collar! If you look at the pictures below, you'll see what to expect from your finished collar. I hope these give you a sense of the difference tailoring can make in a garment. In some versions of this coat, the collar has looked a little flat to me, but pad stitching will give you a shape with lots of body and a distinctive roll around the neck.
Next you're going to steam your under collar and leave it to dry overnight. Pin it around a tailor's ham as it will be rolled around your neck.