I live in a Victorian semi, which is very expensive to heat in the winter.

Cavity wall insulation is not an option.

The windows were all replaced recently window with modern double glazed windows.

There is still a discernable chilly draft feel in certain rooms around the
decorative wood panels under the windows.

I've wonders if I could fill the voids behind these panels with expanding foam
to increase insulation.

I've also though of adding internal insulation to the inside face of each
external wall.

I found this:

http://www.youtube.com/watch?v=sLZXQtlI7eQ

It's basically an insulating lining paper.

I also lose heat through the floor boards to the cold cellar.

Thoughts/advice much appreciated.