I'm an unmarried father.My twelve year old daughter has asked to come live with my soon to be wife and myself.I now reside in Australia.My daughter lives with her mother Monday to Friday and spends the weekends with my parents.They both live in Ireland.My daughters mother and myself had broken up over ten years ago.. I have a strong relationship with my daughter and can offer her a more better and comfortable life here... Where do I stand??

What does your daughters mother have to say about it? Where you stand is on what mom wants/agrees to.
I don't know the laws with Ireland and Australia but I think you should be able to work something out with the mother. You need to go for a custody order whether it is you getting primary custody or getting her for summer months or whatever you should go through court.

You need to file for a modification of the custody order. A judge will then weigh pros and cons (including your daughter's preference) and make a decision.