I'm looking at it as, I am working to be organised enough that IF there is an issue, I can look after my immediate family at home without taking resources from others. DH and I can both WFH if necessary (although from something I saw earlier today, my device may be required by others if my needs are not high enough priority - in which case, I can get my emails on my phone, send home to my gmail enough useful docs for a week, and work on my Mac instead - and then start badgering my boss who would likely still have his device, to email me more docs which can be done remotely).
I have looked at resources that would be useful for DD - and we have already warned her that she would be doing projects etc and keeping up her schoolwork that way, even if school don't set any work beforehand or remotely. She is not an exam year, but has State exams next year so plenty to work on.
I have decent storecupboards anyway, due to our busy lifestyles. I am trying to make sure to keep sufficient fresh stuff at the moment, like milk (DH and DD drink litres of it each week!! They're like calves!). But I have some alternatives, like a bottle of almond milk for coffee, and a couple of tins of evaporated milk to add water back into. Even without doing a massive shop on my way home to lockdown, we could manage a fortnight relatively easily I think.
I have filled the scripts for myself and DD, and got my GP to give me a course of steroids "just in case". The reason being my GP is near my office in the city centre, and the out of hours doc is also city centre for that practise. As I am asthmatic, I have needed them a few times in recent years, so I now have them in my possession and, if need be, I can ring my GP for advice and be able to avoid going in to her. Or else, I would need to go to a local GP who doesn't have my history - which is not ideal. But the theory is that this should reduce pressure on medical resources if there is a problem, because I can manage at home for a while and start treatment plans myself (under medical advice by phone).
Yes, having others still working would be useful, to get fresh food delivered, get medical advice, or other kinds of help.
But first and foremost, I will work on trying to be as self-sufficient as we can be for ourselves and take pressure off the other services. Admittedly, part of my plan involves a quick trip to the supermarket on my way home if we get a lockdown situation - to get fresh milk, cheese, eggs, fruit and veg, and some meat to cover a few days at the start - as who knows how long it would go on for and my home supplies are not inexhaustible. But that is all I would be looking for. And it would mean not needing to look for others to come to our aid for at least 2-3 weeks if I did that.