Smart meters replace the main billing meter.
What I think you want is a plug in meter to track individual consumption. Some of them do not read correct with smaller loads. Mine was a cheap one from I think Lidle. They have them at about £5-8. The Navitron one does but costs more.
So dep on the size of the loads you want to monitor either would do.
They both can be programmed with the p per kWh that you pay so can display the £ cost of each item. When chasing our usage I tried to leave the unit plugged in for a reasonable period again dep on what the item was.
So things that use power as a constant or in a cycle could be measured for a few hours or a cycle (washer, tv ect). Things that cycle on & off or get affected by human intervention need longer (fridge & freezer or heaters) to get a better average.