You are looking nine years ahead and by then your level of cash will be substantially larger with spouse’s lump sum and the disposal of some properties. You are looking for opportunities for cash while being quite risk averse. Your only major expense could be a property purchase abroad. I’m not clear if your intention is to be owner of a home in one of the countries.
Buying years for spouse may be one of the better options but ironically you will be well able to manage that from salary deductions and that probably will have little effect on savings, other than adding more cash in the form of an increased lump sum for spouse at age 60.
Cost of purchase of 10 years will be around 27k per year (gross). That will yield around 40k extra lump sum on retirement and 13.3k per year pension. Is that value? You are then looking at indexation and life expectancy for both of you to estimate the benefits of the purchase.
Purchasing 10 years’ service I think could cost you net 1,500 approximately per month. Net current take home salary is 7,380 per month and this will increase further when your salary rises by 14k per year in four years. Buying the extra years could be manageable from current take home amount. So that is a quite early decision for you; whereas a lot of the other factors may be less immediate options (other than clearing mortgage).
Buying service for you is much less clearcut because of early retirement implications. You will need your HR to explain that to you.
On state pensions will the surviving one of you be eligible for a pension.
There are big decisions both personal and financial but you are looking nine years. It is reasonable to feel vulnerable as you mentioned. It seems to me that
It would help if you have a clear idea if you are going to have a ppr in at least one country.
You need to clarify as much as you can around state pensions and also implications of Spanish residency on disposal of Irish properties for CGT.
You will be cash and asset rich as your spouse retires but your household salary/pension income drops from165k to over 40k, including spouse’s state pension. Despite your other resources, it’s a serious drop.
You mention about part time work if necessary; is that in Ireland? Instead of retiring at 53 would you consider a career break for up to 5 years and give yourself the option of returning if necessary. You should be able to return on a part time basis. Giving yourself the choice of returning part time to a 60k position might be a better prospect than other part time work maybe at a fraction of the salary in your mid to late 50s. You forego a lump sum of 36k but only a pension of 4.5k but you can still retire after a career break on increased lump sum and pension. Given the likely scale of your cash and other assets this would not have a huge financial impact and it could lessen the feeling of vulnerability.