Strawberry plants are perfectly hardy and they should be fine if left outdoors. A bit of cold weather will probably do them good! Just clean up and cut away any old foliage and plant debris that has accumulated in order to destroy overwintering pests and diseases. Move the pot next to a fence or wall then this will help to shelter the plants from the worst of the weather. The main thing to look out for is that they dont get too wet. Check that the pots have plenty of drainage holes and that the compost is free draining to prevent the plants from rotting.