I didn't expect so many replies, so thank you.
To summarise, I'll say that I have parked the idea of moving in the immediate future, but it may be a medium or longer term consideration.
This is partly because my parents (in their late 90s) and still living in their own home, are 5 hours away from me. Moving closer to my children would increase that distance.
Let me start by saying that some of the comments based here are not correct, but I don't want to say too much as it can be 'outing'.
For example, moving would not change where my husband has his treatment. He'd just be travelling from a different direction.
I felt hurt at some of the comments saying 'He's dying, what are you thinking of?'
Note everyone with cancer is about to die imminently. As a kind poster pointed out, some people live with cancer for many years. At the moment, his life is around 70% 'normal' in terms of what he can do.
I considered moving because I've spent my life compromising and not being able to do what I really wanted.
When I married I relocated, leaving my professional job and friends because my husband was the higher earner and already owned a house.
I wanted to move closer to my parents but he wasn't keen (work, again) and when our children were settled in good schools, we felt that ship had sailed. I've spent decades driving long distances (often on my own) to see my parents.
We became grandparents late in life- almost 70- and I'd love to spend more time with my family now (having not been able to with my own parents) while I'm well enough and able to help out. I know they'd like that and I' d not 'take over' or be round there every 5 minutes!
However, I do appreciate that if my husband's years are limited, I should be mindful of that and keep relocating for the future, although at the same time I feel I've compromised all my married life for one reason or another.
Ultimately I want to be near my children. I may have to postpone that for some time but I know where I'd live , my only thoughts were it would be nice to get 'established' as a couple, rather than me doing it on my own and trying to build a new life when I'm older.
There are options which have been mentioned- use an Airbnb more often (we've done that already). We'd considered renting somewhere, but the prices are so high and the outgoing would be money 'wasted' so that probably isn't going to work. If we bought a flat nearby there are so many pitfalls with leaseholds we're wary of that.
Thanks to everyone for their input. I won't come back but sharing this has cleared my mind a bit. Thank you 