Depending on the type of pension plan he has, he (and/or his employer) may be able to make a last-minute contribution to it before he retires, avail of full tax relief at his highest rate and then withdraw it all as a lump sum immediately after he retires, tax-free. This doesn't work in everyone's circumstances, but it's worth asking his broker to establish if it applies in his.
I would be reluctant to recommend that your father invests the bulk of his life savings in a single asset in a single asset class on a small island. If he's worked 40 years in construction, then my guess is that he would feel comfortable investing in something that he understands. But remind him that he's lived through several examples of how things can change dramatically in a short space of time, in ways that nobody really predicts. At one time, shares in the pillar Irish banks were considered to be literally as safe as houses. It was unthinkable that anything bad could happen to an investment in them. Until it did. More recently, look at the dramatic changes that have been brought about by Covid-19 and are still unfolding. When I was growing up, if anyone had suggested that owning a pub in a busy Irish town town would be anything but a thriving business for life, they'd have been laughed at. Now look. My point is that no single investment should be thought of as a suitable home for all of one's life savings, no matter how attractive that investment might seem now. Things can happen that you wouldn't think possible today. Split it up - diversify.