I'm taking the mirena (levonorgestrel) coil out because of constant breakthrough bleeding-will I have this if I go back on the pill straight away?

Maybe. Before you take the Mirena (levonorgestrel) out you may want to consider a 21 day regimen of an estrogen pill. It may stop the bleeding and let you continue with the mirena (levonorgestrel). However if you do take it out you may have irregular bleeding for some time before your body adjusts to the pill.