According to Ofcom, awareness of this scheme is very low.
If you or someone in your household claims Universal Credit, you could switch to any of the tariffs available.
All major providers also include people on Pension Credit, Employment and Support Allowance, Jobseeker’s Allowance and Income Support.
Some providers might include additional benefits, like Personal Independence Payment and Attendance Allowance.
The person receiving the benefit needs to be the main person on the contract.
Service checker here: https://www.ofcom.org.uk/phones-telecoms-and-internet/advice-for-consumers/costs-and-billing/social-tariffs
(AIBU to try and save Mumsnetters some money?!)