RE: the s&p :
Disclaimer: I'm an idiot who has no financial qualification. The comments below are I just what I do.
You could hire an accountant eight years from now, hand over the pile of investment receipts and ask them to handle the deemed disposal. Or opt to sell everything, settle up the tax and reinvest. The broker will generally list your p/l when you sell and you just pay the gov 41% of the gain. It's not "efficent" but it's better than losing money through inflation by inaction.
There's also the admittedly small hope that deemed dispoals might be scrapped within the next eight years.
The S&P is carried by a tiny number of tech companies. For a single fund, I would consider either the FTSE All World Index or the FTSE Developed Index, the difference being the All World has around 10% emerging markets exposure (but costs slightly more) while the FTSE Developed does not. There is also the MSCI World which despite its name has only Developed countries but less of them compared to the FTSE Developed so it's more concentrated.
This is the return of the Irish Life Map 5 fund mentioned in the OP which is listed as being medium to high risk. I picked it as it has around 14% emerging market exposure similar to the FTSE All World index :-
And these are before you pay their fees :-
This the FTSE Developed via a Vanguard ETF you can buy for no commission and costs just 0.15% per year :-
Key facts and comparisons for Vanguard FTSE Developed World UCITS ETF Acc (VGVF | IE00BK5BQV03) ➤ justETF – The ETF Screener
This is the Vanguard FTSE All World ETF which costs 0.22% mostly for access to the emerging markets:-
Key facts and comparisons for Vanguard FTSE All-World UCITS ETF (USD) Accumulating (VWCE | IE00BK5BQT80) ➤ justETF – The ETF Screener