Tiling Large Kitchen/Diner floor

Hi guys,

Looking for some advice/opinion on the tiling of a large room in our semi-d. We have a back extension which brings the area of the kitchen/extension to about 40 square metres. At present it just has a cheap and cheerful laminate down. But underneath we put a good quality insulated underlay. It makes for a lovely warm room eventhough it is quite big.

Anyway we want to have it tiled with polished porcelain tiles and I'm wondering is there anything worth putting under the tiles that may help keep the heat in or do the tiles do that job anyway? Its onto a concrete floor.

I suppose I'm not entirely sure if the underlay currently down, as expensive as it was, actually adds to the warmth of the room? We don't want to end up with a freezing cold floor with the tiles down?

Don't really know enough about it basically. Any ideas??

Thanks