Yes, Look After My Bills can find you a cheaper tariff even if you have a smart meter.
Most smart meters in the UK are first-generation smart meters; which will continue to work if you change supplier.
First-generation smart meters lose their ability to send automatic meter reads to the new supplier (they are only smart enough to work with the supplier who installed them!)
This means you will have to manually provide your new supplier with meter readings, usually once a month.
Not sure how to read a meter? Check out our guide.
A few suppliers are trialing the second generation smart meters, which are able to send automatic meter readings even if you switch energy supply.
Expect to see more installations in 2020.