1.) Knitwear. Jumpers, cardigans, woolly hats in burgundy/brown/white...
2. A cute skirt.
3. To top it off, a good pair of brogues/loafers/boots.
OK, I lied, maybe you need a fourth thing - a cup of tea.
What I've found is, if you're an English student, you dress like this all year. Because you're English, and in England it's basically Autumn weather all the time.