My only caveat is about accommodation
I spent 3 months in Dublin and 3 in Oxford. The time spent in Dublin was the best. The city is beautiful and in a short period of time you are able to feel at home. The only thing is that if you are from a tropical country, as I am, is quite hard to get used to the irish weather and because of that I do not recommend students to stay far away from the school... which was my case - I had difficulty in waking up very early and once the school was far from where I was staying sometimes I used to get late to classes. So, my tip is: stay as closer as you can to the school. Dublin is an easy place to find accommodation by yourself, so I think that the best thing to do is to book one month accommodation (also to know the family, the house's location and so on), because than, if you are not so "lucky" you can search for somewhere else. I mean, If you book all the period you won't get your money back, you will only be able to move to another house. However, it is important to say that Kaplan (ESPECIALLY Oxford's) is not very receptive to changes in accommodation, and that was my biggest problem. In England I had the worse experience with hostfamilies of my life!