Is it more economical to have the central heating or the gas fire on?

Question

Also, should i turn off the radiators in the rooms i dont use as much?

What temperature (degrees C) is the ideal temp to set it at?

Answer 1

use the central heating as the fire place only heats one small area the furnace properly uses the same amount of energy and does the hole house our heat is set at 68

Answer 2

Neither.  :-)  I don't know how electricity vs. gas breaks down in the UK, but in the US it's comparable.  A gas fireplace has the same problem ALL fireplaces do, the heat goes up the flue.  They're pretty, but inefficient as can be.

Plus burning gas puts a lot of humidity in the air, so you're adding cold dampness to the whole house.

You're best setting the central heating to a low number like 60 or 62 to keep the house livable, and using electric space heaters in the rooms you actually occupy.