Keith grow them in the brightest window that you have. If you can rig up some extra lighting that may help as well. You can trim Dahlias if needs be and considering that they will be growing under low light conditions, to remove flowers maybe beneficial. Is there a Dahlia Society over there that you could contact for information from experienced growers under your conditions?

I Googled growing dahlias indoors. Basically they say what Whoz said. Grow them by a sunny window or under plant lights. I think if you are just able to keep it alive over the winter that would be a victory for you.

Multipling gladioli
 

Attached is a photo of one of the gladioli from last season that has multiplied just a little bit. Have not tried counting the new growths yet. This one has multiplied far more than any of the others, most have at least doubled or produced upto 5 replacement corms, but this one and one other went mad multiplying.