We use a gas fire for downstairs and aircon upstairs. We bought 4 panel heaters when we first bought the house and left them on 24/7, they were absolutely useless, didn't even take the chill off!
Our friend just brought 2 and I must admit they dont heat the place up much..
But we have now brought a heater for the upstairs bathroom , because the towel heater is a bit like the panels.
And the gentleman in Euronics was very helpful with a new electric heater, where the heat can come out from both sides and top, he uses one to heat his own home.
Last night we were nice and warm even had to turn it off.
We use a bottle gas fire in the lounge, usually get good offers on them in Brico depot, a panel heater in the bedroom use very little electric so can leave on all night if need too and an electric heater in the bathroom looks like a small aircon unit( again a good price at Brico.