The current British railway scene maybe slightly different from the US. I assume you wish to move to Britain to be in contact with the BOC. However, I cannot help with rail companies in Ireland, because I have no contact with them.
I am unsure of the full scope and training for conductors in America. In the UK, conductors have responsibility for passengers, safety, security, fare collection/ticket inspection, etc. They are employed by the Train Operating Companies (TOC), and each TOC will recruit their own staff. It will therefore be necessary to apply to a TOC for a vacancy, and it is unlikely that your present experience will count for a great deal because the rules etc. are different here, so you would need to undergo the full training package, although your experience may help with the selection process.
Depending where you wish to settle will be which TOC(s) serve that area, so I cannot suggest which to contact. I may be able to point you in the right direction if you tell me where you want to live.
With love and prayers,