www.menopausematters.co.uk/perimeno.php
Compare the estrogen and progestogen in your current pack or patch.
Norethisterone can be prescribed on its own (it's used to delay a period and for heavy periods.)
If you cannot get your current HRT, your GP could prescribe an estrogen-only tablet, patch or gel, and a separate script for Norethisterone.
This is clearly beyond the knowledge of most GPs it seems.