Hi Zacchaos,
Many thanks for your detailed reply. I double checked the PAYE Anytime site and although my wife's details are present in the personal information section, there is no option to transfer any tax credits between us. It simply lists my own tax credits similar to the case for a single person. We are also eligible to receive a home carers tax credit (800 euro) since we have a dependent child and my wife is not working, however this tax credit is "greyed" out so I am not able to apply for it online.
As you suggest, I will give the revenue a call to see if there is any progress on updating their systems to reflect our circumstances.
Thanks.