Thanks for posting the BJSM link. This was the framework we utilised early on in the pandemic, though our experience was that it was frustratingly slow for most athletes with mild illness, many of whom reported that had they been living in ‘normal times’, they would likely have trained through it (although this isn’t necessarily a good approach!!). There are some newer updated guidelines available now, but I have found that the following (link below) gives a good, pragmatic overview, and most athletes with mild illness can be back to normal training in 7-10 days. However, if in doubt, it is never a bad idea to be conservative.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9170595/pdf/main.pdf