electricity is unfortunately three times the price of energy from gas, but to warm a single bedroom, I agree an oil-filled rad is suitable. It gives out a more even heat than fan heaters or ordinary convectors, because the oil takes ten minutes or so to warm up and cool down, and it has a larger surface area giving off heat.
It is also safer, as it will not start a fire if a curtain or bedclothes accidentally fall on it.
be sure to get one with a thermostatic control, and if your room is largish or badly insulated, look at a 1500W heater. If it has a high/low switch it will bring the room to a reasonable temperature and then you can turn it down overnight. I am not keen on integral timers because they go wrong long before the heater itself, and dome are noisy. You must not use a timer with a fan or convector heater as it will come on when unattended and there may be flammable material on or around it.
Bedroom radiators are typically about 1500W output but don't usually need to run at max heat for long. When I was living in a house I was renovating, the bedroom needed a 3kW fan heater in frosty weather, until the day I insulated the loft, when it dropped down to about 800W.
At this time of year, supermarts and hardware outlets stock heaters, but as soon as cold weather comes, they will be inundated with buyers and will be sold out until next year. A cheap own-brand of electric heater has exactly the same heat:electricity:cost performance as the most fashionable and high-tech electric heater you can buy (sellers of expensive heaters may try to trick you).