I'd give them a spell in a well ventilated area in the greenhouse, certainly overnight to start with. They may well bolt with the change in temperature during daylight hours.
As you may well know, radish should be sown a few at a time on a weekly basis, otherwise you get a glut of them.
You will still get a few fresh ones if you start them off now ... 3" pots filled with fresh compost and a couple of seeds in each pot. If they are started in the greenhouse they should be okay as long as you dont let them dry out.
Last week I started some carrots and beetroot off in the polytunnel, they will be ready before the spring.. there's still some heat in the sun, so dont be afraid to experiment.