Short answer: don’t.
Long answer: we had one in a rented flat. At the time there were two providers, Scottish Power (useless ****) and EON ( considerably less useless but more expensive in our market) who did the required Economy 11 package. Most muppets in the call centres dont know it exists and try to sell you Economy 7 which you WILL end up with despite repeated emphasis on the 11. Once all thats ironed out and your bills return to “normal” you will be ready to rip it all out and cut your losses following what can only be described as a violation by even terrorist standards when winter visits.
The equivalent gas system would be cheaper and the performance should be identical in terms of insulation. Its a no brainer until such times as gas becomes more expensive than electricity. Long way to go yet, even hydrogen would be cheaper to pump into the grid.