Gas Rayburn Nouvelle and fireplaces

[Fab41]

We move into a 1930s semi in january, all going well. It has an open plan living room and dining room, and then a big archway into a kitchen extension.
Heating and hot water is from a gas Rayburn nouvelle which i love the look of, but am worried about the cost of running it. We also have an open fireplace in the dining room and living room, and i have never had open fires before.

Any advice? We currently have night storage heaters, so this amount of heat is overwhelming!

Bump. Does anyone have a gas rayburn for heating, water and cooking? Would really love an idea of running costs or even how to use the thing, i have never used one before.
With the fireplaces, is it cheaper to use these for heat instead of central heating through the rayburn? Logs look expensive, but again, I have no experience
Thanks