If you are taking poison (suicidally, or accidentally) you would not be committing an offence.
Taking misoprosol (an abortifacient or labour inducing drug) does nit come in to that category.
There is no lack of clarity in English law. Abortion is regulated. There have been no blurry lines about the dates when it is legal, and it has never been permitted as DIY. Indeed some of the rationale for the original act was to prevent DIY.
There are only 4 countries (I think) worldwide which permit abortion up to the onset of labour, and none in Europe.
I really do not think there would be any support to make a change to the law to permit abortion to term (which is how a I read what MrsTerryPratchett recommends) and the latest revisions, to the contrary, reduced the time limit other than for TFMR. Nor would I expect there to be support to reduce the requirement for HCPs to prescribe or perform.