Replacing my storage heater

Chocolatespiders

I live in an all electric house. I have one small storage heater in kitchen and a large one in the lounge. I never have the lounge one on as we are out all day so seems pointless to have a hot house all day when we are out. So we plug a panel heater in during the evening. 
I would like to replace the storage heater with something wall mounted and smaller. I do have kitchen one on in winter and have clothes airer by it. 
If I got an electric radiator such as Dimplex Q rad could it be wired into the off peak economy 10 electricity rate and I then only use it during those off peak times? Or would it be best to change my electric tariff.
If I change the lounge heater would I also need to change the kitchen heater? 

Thanks in advance.