Children (and spouses) are resilient. My father regularly went off for six month trips to the other side of the world for a good part of my childhood. Granted there wasn't a war situation (6 Day War excepted) and we just waited for the next postcard to arrive.
Based on all you have said here, the first thing I would do is consider how important your visit to the UK would be in practical terms. I don't mean to be cold-hearted, but first you need to consider how much your presence would be of practical use to your father, or of significant meaning to him, or whether this is "merely" about fulfilling your fillial sense of duty / expectations of the family etc.
As mentioned, the whole skype thing works.
My father dies last year, and due to covid the siblings in the UK couldn't travel.
However, regular video call updates, as well as purchase and of 'special' food he liked via the internet, and booze, showed thy were aware he was faltering.
You can always be " A Cool Dad" and chat on Skype, Fartime. whatever.
They'd love it.
Probably Mum will spoil them a bit too..
Kids bounce well from stuff...don't fret...and maybe do a count down calendar to coming home or something.
It teaches them to measure time and expectations.
SWMBO, a primary teacher of 42 years did benchmarking stuff for decades.
Kids love it. Lets them share your adventure rather than feel left out.