hello
@JojoB54 and a warm welcome to DTP
I doubt you will entirely stop fretting, any more than you would if you spent a couple of days away shopping ... something may or may not happen with your father but that's the case if you only leave him a short time, and he's your father, you care about him, so you will fret to some extent
you are organising a live-in carer whom he knows, which is good and will help to ease your mind ... make sure you leave your contact numbers and those of GP, social worker, family, friends etc who would support if needed ... to give the carer some time to themselves maybe arrange a befriender or other carer to visit each day ... leave details of your dad's routines, meds, likes, dislikes etc just so the carer has something to refer to ... and, of course, you will be arranging to stock up/deliver food and any essential supplies, plus a few treats
think ahead and have a plan for what you will do if you do absolutely have to go home ... check with the cruise company, they will have come across this before ... being prepared will stop you worrying about it
you know your father, whether he will get agitated if you mention it beforehand or a little 'drip-feeding' over time will let him get used to the idea ... mention this as a break for him too, or you've taken his advice to have a treat for yourself, or that your OH has surprised you so you couldn't give him much notice ... be positive, tell him how fortunate his lovely carer can help out, you'll bring him a souvenir, maybe leave him a brochure and itinerary so they can track your travel ... probably don't dwell on what you tell him, be brief and follow with a treat so his experience is positive
once you have covered all bases, you will know that you've done all you can for your dad and the carer
enjoy your cruise