how many / what percentage of our population has had it
We may never know the answer to that.
That's a very good point Call
Puzzled, in answer to your questions, I think this is the most analysed set of data in history .
The number of tests carried out is reported every weekday. Nearly 604,000 on Friday for 60,000 positives, so about 10%. WHO recommends that a pandemic "under control" should have a positivity rate of 5% or less.
I've found people don't really have a grip on the impact of the pandemic in terms of number. A survey in Scotland a little while ago had some people who thought 10% of the population had died. That would be 500,000 people in Scotland alone.
The Travelling Tabby sites have lots of metrics, I'm a bit addicted, I think. The Scottish Government were publishing a lot of detailed analysis for each Local Authority up until we went into lockdown again. The link for the most recent is at the end of this post. Can't speak for rUK, I haven't been tracking that, but I'm sure someone somewhere has been doing the same thing.
Don't know much about false positives, but I guess the important thing to be aware of is trends, so the proportion of false positives will be steady and we'll see how the overall total of positives varies as time goes on.
www.gov.scot/binaries/content/documents/govscot/publications/strategy-plan/2020/12/coronavirus-covid-19-local-authority-indicators-and-levels---22-december-2020/documents/covid-19-strategic-framework-summary-indicators-and-trends---22-december-2020/covid-19-strategic-framework-summary-indicators-and-trends---22-december-2020/govscot%3Adocument/COVID-19%2BStrategic%2BFramework%2B-%2Bsummary%2Bindicators%2Band%2Btrends%2B-%2B22%2BDecember%2B2020.pdf
July 23 Limerick (continuation of July 21)