Toadflax, common centaury,field scabious, bog asphodel,golden rod,common mallow, betony, are some that flower beyond September. None are woodland plants though. The wild plum and the pussy willow are two trees that, eccentrically, sometimes put out flowers in early Winter. Easier if you're a gardener and can grow imported species; prunus subhirtella, a winter flowering cherry, flowers from late Autumn and there are others.
Yes, I thought of Lords and Ladies (ahem, our ancestors were somewhat basic in naming plants, and that some names for this one were worse) and it is definitely a woodland plant. But it is notable for the red berries more than for the flowers.