Generally, the teacher will cover examples of some entrance exams from previous years. End of Januray sounds quite early so perhaps teacher is not intending to cover them until next month.
Generally, they are asked to write an essay in Irish, maybe something along the lines of My favourite person, or A day I spent Shopping etc.
Also required to write an English essay I think.
Maths is usually what's in the Maths curriculum, although I think there's some Simple Interest questions usually, but they're not on the Maths curriculum for 6th class.
IF it is an aptitude test as you say, then things can't be really covered in advance. They are purely to test the general intelligence of the child in question.
Hope this is helpful in some way.