I'd missed the news about this so am sharing in case others have too - you can pay £20 for an annual certificate which then covers most HRT prescriptions. It's just under £20. I only get 3 months HRT supply at a time and also pay for Oveston cream, so for me this makes a lot of sense.
More here:
www.nhsbsa.nhs.uk/help-nhs-prescription-costs/nhs-hormone-replacement-therapy-prescription-prepayment-certificate-hrt-ppc