Very sage advice Jaqs, but this is something I think about all the time, even though I am blessed with fairly rude health. Anything which I do of a technical or computer nature I make a point of involving my wife. Apparently stupid things like how to identify the fault/fuses/switches and get the house back on line in the event of a power-outage; how to open the electric gates in the event of power failure; how to get the computer and ancillaries up and running in the event the power goes off. I try and discuss anything and everything which relates to tasks which I carry out now...and which she would have to do in future.
A concern relates to credit cards, as when these were first taken out, decades ago, they were taken out in my name, with my wife's name as a secondary cardholder. Which means that in the event of my demise, my wife's cards might be withdrawn. But hey, you can only do so much. The most important think is that we have Wills made out by an English lawyer in Larnaca (Marion Carter) which we update every couple of years. And we are very fortunate that our daughter and family live nearby and would do whatever it takes, in the event.
Must admit that in the event of my wife passing first I would have a helluva job understanding the logic - or complete absence of - of where pots, pans and baking utensils are located in the kitchen. She's an absolute nightmare