I cannot say anything about the prejudices against UKistanis apart from the fact that some are employed at $employer and do not get shot. However, seeing that I immigrated here as well, a few comments about moving:
* Irish time: learn it, love it. Yes, the Irish have the same timezone as the UK, but the perception of time seems to be quite a bit different. Don't get upset if things take longer.
* public transport can be the best or the worst experience you had. Sometimes both during the same journey.
* If possible, avoid getting a phone line and internet connection from the state company. UPC is better in that respect
* Tesco Mobile will probably be your best choice as a carrier if you do many calls abroad
* Do not trust the O2 callcenter on ANYTHING! They managed to tell me 3 inorrect things to 3 questions I asked.
* for renting a place,
www.daft.ie is quite nice.
* remember that Ireland is a country of emigrants and immigrants. You will hear and see quite a number of languages. If your native language is not English and you hear it spoken in the street, it can be a conversation starter
* Ireland is a good place to quit smoking. If only because that and going broke are the only 2 options.