a lot of my friends think im mad to go....
Oh, you're not mad to go. It's mad not to consider moving to a different country for a while, if only for the experience.
Anyway, what you need.
Most important thing - make sure you've got the European health care card. It's pretty important, because it'll mean avoiding any hassle if (touch wood!) you need any health care while here.
Obviously, make sure that your passport doesn't run out anytime soon.
Errm..will you have accomodation sorted for you? If so, that'll make life much easier - but if not, I'm sure, even in Gdansk, it won't be hard to sort out
Make sure that you've got the means to get back to Ireland quickly if needs be - I've heard some horror stories of people being stuck in Poland without any support network, and it's just wise to be able to go to the airport and 'go home' without any notice.
Hmm...Polish is a nightmare to learn ;)
Ack, if you have any questions, feel free to ask...I'm no good at telling people what to bring, I came here on the spur of the moment :P