It would have been better to sow the seeds in spring so that they would geo as the light was lengthening. Have they already germinated? I'd keep in the potting shed over winter but you may find you need to re-sow next March. Keep the compost just slightly damp.

Hate to disagree, but all of those plants are best sown when the seed is fresh. they germinate much better than dried seeds.
I keep my Autumn sown seeds in a cold greenhouse, where they get cold, but are protected from the worst of the winter rain.
Once seeds have been sown and got wet then it kills them if they are allowed to dry out,so yes, keep them watered, just not drowned.

Thanks for the replies. I was going along with the natural cycle, thinking that, if left, they would shed their seeds onto the ground below, and they would lie there all winter, ready for the Spring.

Exactly they would have waited until spring to germinate... So keep them as cool as possible.