In the beginning of Prince Caspian, Susan wears a maroon, gray and white school uniform with a blue-and-yellow striped tie. The blazer has a pocket and a lapel. It falls to mid-hip. On the pocket, there is a signia, probably the symbol of her school. Her skirt is just a straight skirt, seamed on the sides and possibly the back. It has a waistband. The shirt is a dress shirt, but it is hard to tell what the cuffs look like.
Simplicity 3688 would be ideal for the blazer, since it is about the same length. The only difference is the lapel is rounded, as opposed to pointed. The skirt that goes with this pattern would be workable, or you could just fudge it. ;)