[Bungleaio]

Socotoap is right conservatories leak heat like it's going out of fashion extra insulation is key.

Storage heaters will be cheaper than oil heaters but by the evening they will have been cold for a while so supplementary heating will be required if you want to use the room then.

Heating under floor would be good as the floor will store some of the heat and radiate when the pipes are not being heated by the boiler. Obviously the floor needs to be broken out and re-laid with the pipes in so can be quite expensive and messy.

Installing a rad is the easiest option and will heat quite well. However unless you've got zone control to your boiler or the thermostat is located in the conservatory the rest of the house could be warm and the conservatory cold, this will also apply to the under floor heating.