There's a fairly good chance of your fuschias blooming over the winter. If you have cut some of them back a ton they may take a little while. I have fuschias that are blooming right now in my dinning room. There's a chance that this will be the only time this winter that they bloom but theres a chance they will bloom again. Last year I only had one inside over the winter but bloomed and it grew a lot but it defoliated in late winter. Your greenhouse is probably an ideal place for them. I plan on moving mine to a greenhouse that I just purchased as soon as it is up and running.
good luck and happy newyear!

-DB

My "Gartenmeister" was blooming beautifully in its outdoor location until I forgot about the frost warning and left it overnight... It died to the soil, but fortunately the roots were fine. Now it is sending up healthy shoots indoors, but I know it will be a long time before it blooms.