I am a nurse from Ireland. I studied and worked there before emigrating to Australia for work in 2008. I saw the economy tanking and knew that health care would be one of the hardest hit areas.
You are correct there is no such thing as an OB nurse in Ireland or the UK. anyone who wants to work in maternity needs to be a midwife. This can be done as graduate diploma if you are already REGISTERED with An Bord Altranis (Irish Nursing Board) or as an under grad degree in Ireland. If you do have the above qualifications you will not be able to work on a maternity unit. contact Irish Nursing Board, An Bord Altranais
for more information.
However your biggest problem is getting a job. local graduates are not getting positions currently so I would expect an overseas graduate with no experience would find it near impossible. Also there is no long orientation like the US. Because of the high exposure to clinical areas as a student (approx 50% of time) Orientation is usually 3-5 DAYS.