Storage heaters have a bad rep. I think this is unfair. I have lived with them very successfully in well insulated/ modern properties, and very unsuccessfully in poorly insulated old houses
There are two critical things and one brucey bonus when it comes to these heaters
Critical 1 - you need a well insulated property, or you have the too hot in the morning, too cold at night issue
Critical 2 - buy storage heaters that automatically adjust the input charge to reflect how warm the room is at the time. This way, they do not over- charge on mild evenings. These ones do not cost much more than dumb, basic ones. It is a no brainer to buy these
Brucey bonus 3 - you can buy dual supply storage heaters. These are much more intelligent and allow you to use them as fan heaters too, drawing current at any time of day you choose. But these are very bulky and expensive. So you need to decide, but a dedicated £30 fan heater is a much cheaper way to go
All electrical heaters are 100 per cent efficient. Electrical wholesalers try to sell some voodoo, bullsh1t German ones as being miraculous money savers. I do not believe a word of it, and the things cost a fortune. I recall one saying that because it had a very accurate thermostat, it used less energy than ones that allowed the rooms to get too hot, no effin sh1t !!!! But some loons fell for it
Buy a boring, well established english brand like creda or dimplex. Been around forever. Parts and backup are available. Piece of cake to install, repair etc. far less likely to give trouble than some unknown imported crap in my opinion
Provided you keep it to 3kw i think, you can use a little timer that fits in a standard wall box if you need to time the heater