Installing a smart meter

Um. I know this is a totally dumb thing to have done but Ive booked a smart meter installation without realising what it is. I thought we just get a little computer thingie that tells us our usage, but apparently we’ll be getting a new main electric box?? Anybody know?
Also, does anyone know if we’ll be charged for this??

You actually get new meters installed and your old ones removed. The computer uasge thingy is called an in-home display. Installation and equipment is free.