It's clear to me that, much like the guidelines for pregnant women, the government
advice is designed to deter idiots from doing reckless things, not sensible people.
Let's face it, if healthy 70+ year-olds are being allowed (encouraged, in fact) to congregate at supermarkets, then the idea that we all desperately need to self-isolate to get through this can be considered *******s.
I'm planning to get my dad to move into a local Airbnb for a month or so to keep him from going mad. The kids and ourselves will be effectively self-isolating from tomorrow and as long as he does the same then there's no real risk in us mixing with him if we're sensible about it.