Prescriptions

As long as your partner doesn't earn more than £935 a month you still get free prescriptions.

https://www.nhs.uk/nhs-services/help-with-health-costs/help-with-health-costs-for-people-getting-universal-credit/

If your partner earns over that amount you can apply for help with health costs

https://www.nhs.uk/nhs-services/help-with-health-costs/nhs-low-income-scheme-lis/

If that is unsuccessful, you can purchase a Prescription Pre Payment certificate. The yearly option works out at £2.20 a week and can be paid for with 10 Direct Debit payments.

Although you may have to budget for medication, it's still cheaper to live as a couple sharing a household compared to two single people running individual households.