"If you have a tile floor, then underfloor heating is really effective." Yes I agree, this would be the best solution. BUT you'd have to have your floor tiles removed, the underfloor electric wiring laid and connected, and then new tiles laid on top. So not a cheap option, but the best long term solution. Lovely and warm on the feet, of course and the air above. Ideal. You can also control the timings individually, so - if wished - just have it on in the morning when you're all using the room.