Sorry but this is all a bit naive, what you seem to say here is that the poorer in society will not have insurance while the better off will, it's more to do with the selfish and greedy, the type who believes that the rules don't apply to them and they can do whatever they want without consequence. Most people despite their income will keep their vehicle legal even if it means going without in an other areas, but it's only the criminal who doesn’t have insurance even if their only crime is not having insurance! And criminals come for all socio-economic backgrounds.
As for Community Sentences the government website www.gov.uk has this to say;
If you have a job, the Community Payback work will be arranged outside your working hours, like evenings or weekends.
So no excuses for not feeding your family!