Nicky_Boo, I wouldn't panic about your Mirena, especially as the systemic effects are said to be limited with that method, but if you are worried do go & chat with your GP about it.
You can still get MPA/Provera in the UK - I take it & I know of other members who do too. Given so many of us react badly to progesterone & progestogens it's often a case of taking what you can tolerate or going without HRT, I'm afraid. The "gold standard" Utrogestan is unfortunately like poison to me & with current limited availability of alternatives, choice is pretty restricted. I researched MPA before starting it & would have preferred another option but had tried everything else & found nothing I could both absorb well enough to control symptoms & also tolerate. My MPA was prescribed by a very experienced, top Endocrinologist with my informed agreement & I take the lowest dose so I'm not too worried, especially as I'm considered at low risk for cardiovascular disease. With Evorel Conti/Sequi due back in circulation soon that does bring back another transdermal option for those of us who can't tolerate Utrogestan.