Irish national but UKBA Have my passport, need to travel.

[masongj]

Hi guys,
First off, as a partner of someone applying for an unmarried partner visa, we've found this forum to be a great source of advice, so thanks to the community for their time and effort.

OK - onto my problem:
I currently hold dual citizenship, Irish and New Zealand, with a passport for each country.
My partner has applied for an unmarried partnership visa, so the UKBA is holding my Irish Passport while the application goes through... (3 months and counting....)

I need to travel to Finland for work at the end of this week and my question is, can I travel on my NZ passport? If yes, how? At the border on my return to the UK, do I tell them I'm an EU citizen?
I don't have an EU ID card, or similar, but I do have a hi-res print of my Irish Passport, on which I've travelled into and out of the UK on many occasions.

Having a quick browse through other posts on this forum, I realise I have a somewhat minor problem, but any advice on this would be appreciated.
Thanks in advance for your time,
Cheers,

Mason