Only 3 days? Gosh, how on earth is there time to arrange everything in such a short time? I can only suppose that funerals in Ireland are very different.
Where I am (England), it would take at least a day just to get an appointment with the undertaker to discuss options for coffin etc and it's extremely unlikely they would be available to conduct a funeral just 2 days later.
Then of course there are lots of decisions to be made, including whether to have a burial or a cremation and which crematorium to choose or which burial site to choose. Making those decisions involves firstly researching what's available - often it can be discussed at the initial meeting with the undertaker, but not always - and then visiting the sites, some of which may require making an appointment. I guess, if the death is expected then that could be done in advance.
There's also the decision as to what sort of funeral it will be: whether secular or religious; whether to have music or not (and if so, what music to choose and when it should be played); what readings, poems etc etc; who will actually conduct the funeral etc. So you might need to book a celebrant (or a church minister if it's a religious ceremony) if you don't want to conduct the funeral yourself and they may not be available for several days.
Once you have it booked, you then have to let everyone know - and find out if they're coming or not, so you can arrange catering for the wake.
Arranging the wake (in England that's usually held immediately after the funeral) will probably involve booking a venue and some caterers which, again, means you need to go and visit possible venues and speak to possible caterers and then find some that are suitable and are also available on the day.
I just can't see all of the above being arranged in just a couple of days. It would be an exhausting schedule of visits and phone calls - and enormously stressful!