It's such a hard thing to do, but you must be practical and make some good choices for yourself in the longer term - as you say, while you want to support them, your team are nearly grown.
I'd stop looking at actual houses for now and start to think about your potential life and what you would like it to look like.
What facilities and amenities are important to you (ignore practical stuff thats everywhere like supermarkets etc and think about parks to walk in, leisure centres etc. What matters?
What groups and networks do you want to be in? Are there knitting groups, walking groups etc - whatever you are interested in?
If you volunteer or woud like to, what options are there?
This will give you an idea of potential different places.
I think it's really important to get a feel for a place too, so spend time visiting different locations - fun days out? And do this in winter - everywhere looks better in the sunshine so if you like it when its a bit dull and overcast ...it will be better when its not.
If you need to continue to work, the availability of work in your specialism is key too. And if you don't need to work, think about part-time for a little while, as that can also help build networks and relationships, particularly somewhere new.
I think it's easy to be distracted by looking at houses when what you need is more context about what you want. Of course, you want 4 beds in London. But 3 beds are ok - the kids can share if they all come back for Christmas. Or if they launch you could rent a room for a while for some extra income to cover move costs etc.
And when you say your kids earn just a bit over minimum wage, people have to live on minimum wage so while you might be unhappy that they have to pay you more, the reality is that they're going to have to as a stopgap - and it will help them potentially make decisions and focus on what they want to do, too.