Black or navy tights or leggings and a tunic or short dress that picks up on the colour of the boots.
Your going to have to wear them shopping there are white stuff, fat face and similar autumn tops about that might be the right colour. But you'll need the whole outfit to check for mummsyness.
I've got flat long boots, navy and a Seasalt tunic on and it's to Mumsy for boots with heels.