You kind of think "I've got cancer - I can't see anybody" but the advice on this seems fairly specific and it's only in certain circumstances - ie chemo or clinical trials.
That said my age - 71 - my lung issues (asthma) and the fact that I have type 2 diabetes (albeit only just over the threshold) are reasons enough to be careful.
For me the most compelling reason to be careful is simply that, if you are over 70 with one or two health issues, you are more likely to get seriously ill. This has a knock on effect on A and E. If, for example, it was full of Covid 19 victims, where would they put heart attack, stroke and serious injury patients. People could die not of Covid 19 but because somebody was taking up space in an ICU.
Discovered the delight's of Tesco "Click and Collect" this morning (all delivery slots full until Thursday 26th when I will get a delivery). It works well and there is minimal contact with other people. Dedicated drive through system, the stuff is wheeled out to you and you put it in your car.