I need a lightweight, somewhat waterproof coat to see me through cooler, drizzly days. I have a nice wool coat for dry and cool and a thick winter coat, but nothing for wetter autumn and spring days. Toying with a Joules style mac but it might be a bit sweaty? Would like bum covering but not long and for it to give me a bit of shape (size 16/18). Anyone have the perfect coat they can recommend?