You qualify if, on the date you claim help with health costs:
a) you receive Universal Credit and either had no earnings or had net
earnings of £435 or less in your last Universal Credit assessment
b) you receive Universal Credit, which includes an element for a
child, or you (or your partner) had limited capability for work (LCW) or
limited capability for work and work-related activity (LCWRA), and you
either had no earnings or net earnings of £935 or less in your last
Universal Credit assessment period
Note: If you're part of a couple, the net earning threshold applies to your combined net earnings.
You should present a copy of your Universal Credit award notice to prove your entitlement. You'll need to have met the eligibility criteria in the last completed Universal Credit assessment period before your health costs arose.
See link for confirmation. https://www.nhs.uk/using-the-nhs/help-with-health-costs/help-with-health-costs-for-people-getting-universal-credit/