Your night storage heaters have been using cheaper electricity overnight. The ceramic radiators will be using power during the day which, if you stay on the Economy 7 tariff, will probably cost more than transferring to a "standard" tariff (since E7 daytime power usually costs noticeably more than the "standard" tariff rate from the same supplier).
So, yes, moving to a non-E7 tariff should be less expensive...and will probably entail a different meter.
(I'm no expert on electricity-for-heating, btw!)