If you no longer have your meter read or have to provide meter readings you probably have a smart meter.
If you have had a new meter fitted since January 2009, no longer receive estimated bills, or have been told by your energy supplier that you do not need to send meter readings anymore or have an In-Home Display (IHD) such as the one pictured below, then you most likely have a smart meter.
One way to tell for definite is to look at your electricity meter. If the serial number on the meter starts with ‘19P’ then it is a first-generation or SMETS1 smart meter. If the serial number starts with ‘19M’ then it is a second-generation or SMETS2 smart meter.
Alternatively, you can try using Citizens Advice's handy smart meter checker tool - https://smartmetercheck.citizensadvice.org.uk/