Depending on how the UK fares in continuing to fight COVID, I think all the races up to the end of June are at varying levels of risk. That is because until vaccines catch up, there’s a risk mishandling there will cause other nations to reduce their willingness to allow a paddock that is 70% British to spend time without passing through even more hoops than in 2020. (Let us remember that for most of the 2020 season, despite less virulent strains back then, there were an average of just under 10 people testing positive per week, in a paddock of under 1500 (giving a per-week 0.75% positivity rating), which is rather high).
On the other hand, vaccination is progressing fast enough that I think events in the second half of the season are likely to go ahead in some form. In particular, by the time Australia rolls round in November, I think most of the paddock will be vaccinated (simply due to how distribution is going) and Australia may well exempt the paddock from quarantine requirements as a result.