This may give you warm winter but that’s a hell of a long time to have to be plugged into the mains for.
That's down to people using 2kw elements to avoid having to install a 16amp line- which, ironically is a relatively simple and inexpensive thing to do. 3kw heats up faster and the 16amp line can handle it with ease (this is what your domestic immersion and electric cookers run from). Personally, I wouldn't even run a 2kw element from 13amp plug. It's too heavy a load, constantly for too long IMO. Either do it properly or not at all is the best advice I can give anyone.