insulate this room tomorow how?

================================== Start with a good draught excluder on the draughty door. Visit your local discount carpet shop and buy a piece of felt / felt-backed carpet which is quite reasonably priced, easy to lay loose and almost completely draught-proof. Get a piece large enough to cover the entire floor.

If this is to be a temporary measure you could put polystyrene tiles on the ceiling. They're cheap and if anybody sees them you can blame somebody else for their presence.

Re-assess the situation regarding wall boards when you've stopped the draughts.

Cic.

"Cicero" wrote

Even ignoring all the usual regulations, the OP mentioned a wood burner, so that puts polystyrene well out of the equation

Phil

As the other poster said, first stop the draughts. Use a nail on brush strip for the bottom of the door (after you have laid some cheap carpet) and foam draught excluder around the door frame. Is the chimney open? if it is then warm air will disappear straight up it, close it off if you can or seal the gap around the flue pipe. Rig up temporary secondary double glazing with plastic sheeting, there used to be a product that tightened up when hot air from a blow drier was applied. Hang thick curtains. If you are in a room at the top then get some rockwool insulation laid above the room in the loft. Hopefully that will do because lining the walls and ceilings with foam backed plasterboard means taking off skirtings, electrical fittings, covings, architraves... a very big job really. Good luck and wear a wooly hat.

=================================== Which 'usual regulations' govern how one *decorates* one's own house?

Cic.