So most of Earth is category 4, Australia is category 5, the UK must be something like category 2. There is literally nothing deadly here and the worst we have is stinging nettles and sometimes horseflies.
What would actually constitute a category 1 or less, or a non-deathworld? All I can think of would be an entire world of primary producers but there are established predators in Amalgamverse…
Deathworld categories are judged entirely on the surface inhabited by the dominant cogniscent life form.
Since humans make their homes near volcanic cauldera and in known tornado hotspots, Earth ranks a total of 3.8, and most of that is because of Australia.
They also count lifeforms that are hazardous and toxic to the dominant cogniscent life form.
Category One deathworlds mostly have hazardous seasons [for example, killing winters or killing summers, tornadoes, cyclones or flooding monsoons] or a pernicious species that is known to be hazardous or toxic.
Species from Category Five deathworlds are generally avoided [if they survive to make it into space]. Oddly enough, humans are one of the few species who can stop them in their tracks.
Non-deathworlds, by comparison, have stable and sensible food chains and hardly any naturally toxic life forms. Those that are toxic are mildly so, in the order of discouraging a potential attacker from attacking again. The life forms from these worlds are generally far more fragile than deathworlder stock.
Exposure to deathworlders - even careful ones - is enough to sympathetically toughen up non-deathworlder species. Most cogniscents see this as an advantage and court tourists from gradually incremental deathworlds.