I have read a lot of threads with people worrying about the UK being put into lockdown and what this will mean.
I live in Spain and we have been quarantined/locked down since Saturday and the whole country is in a state of alert.
This is NOT the same as what you are asked to do if you think you have the virus and are asked to self isolate.
If you are self isolating it is because you have the virus or are working on the premise that you have it (exposed to someone who has it, for example).
Lockdown in Spain is a preventative measure to drastically cut the number of new cases by imposing social distancing. I, for example, have no reason to suspect I have CV but I am on lockdown along with everyone else in Spain. This makes it much less likely that I will come into contact with someone who has it and so much less likely to spread, which if everyone in the country is doing, will bring down the number of new cases.
In Spain we can go to buy food, go to the pharmacy, walk the dog (briefly and keeping a safe distance from other people we meet when out), go to the cash point, go to work and straight home again, go to the petrol station, go to help elderly relatives. We can't go for walks or go out to do exercise because even if we live rurally, if everyone did the same thing then social distancing wouldn't work. The point is to reduce contact and therefore transmission, as much as possible.
People are adhering to this because the police are patrolling and asking people they see out exercising to go home. If they refuse, they can be fined.
Most people understand that it's a serious situation and aren't selfish enough to break the quarantine. They understand it's hard for everyone but that we all have to do this to protect the vulnerable.
Most busineses are shut and shops are controlling the numbers of people in the shops so they can remain at a safe distance and not overwhelm supplies.
Public transport has been reduced but is still running (as some people still have to work and need to get there).
Please don't panic that you will starve to death in the event of lockdown, it's not the same as self isolation. Lockdown is to reduce social contact as much as possible but understands people need to eat and work (sometimes outside the home). Lockdown does mean not going out for a walk or to exercise. It's not easy, but plenty of people here live in flats too, we are having to work out other ways to manage.