1) Forget your pension fund. You can't buy it through the pension fund and let it to a relative. Likewise, you should not make a decision on exiting your pension fund to finance a short term property investment.
2) If you own your own home and have €800k in a pension fund presumably invested in equities, maybe buying an investment property is ok. It's a bit concentrated in property, but given that you have a use for the property, that would probably be ok.
3) Now, you need to crunch the numbers.
A: What rent will you be paying for your son?
B: How much will a similar property cost?
C: How much of a deposit do you have?
D: What will the interest rate be?
E: If you are buying a two bed apartment, will you be able to let one of the rooms to another tenant and how much rent will you get?
E: What will the transaction costs be?
4) What are the risks involved in buying?
We don't allow speculation about property prices on Askaboutmoney, but it's important to point out that there is a risk that property prices may fall. This is probably balanced out by the fact that prices may rise.
In any event, given your level of wealth, you can handle a fall in prices.
5) What are the non-financial benefits?
For your son, "owning his own place" would be a huge advantage. Not dealing with landlords. Not looking for a 9 month tenancy every year. Getting to live on his own or getting to pick whom he shares with.
6) Encourage your other two children to study in Galway
If you live in the general area, it would make it very attractive for them to study in Galway. For most undergraduate degrees such as Commerce or the Arts or Science , Galway is as good as any other university.
Conclusion - depending on the numbers
If you can afford it, it's worth doing.