Go to the Polyplumb web site. http://www.polyplumb.co.uk. They have
a an "overlay floor heating system".

Sounds interesting, I'll give it a look. It would have to be really thin,
though. I forgot about the windows in the kitchen. In true Edwardian style,
they go down quite low. The standard worktop height is already above the
architrave and, in fact, will be just touching the sash beading. I'm happy
to raise the floor a little if the integrated appliances can still fit under
the surface, though. The floor won't be going under there, so I can make a
little down ramp.

Christian.