Winter Protection for Tender Plants
The ideal solution for your Winter protection is an OverwinteringPlant Tent. This can be erected during the Winter and then removed when not required.
Alternatively you could also cover each individual plant with a fleecejacket which will also provide the necessary protection. I used these on my precious tree fern last year which came through a very cold winter
I hope that this is helpful, however please let me know if I can be of any further help.