Stopping world travel would’ve worked it out better. Like New Zealand and Australia. Suppression strategy with vaccines would have a solid effect.
If "it's much easier to control population flow into an island" then you still have to step up and control it. The UK government did not even show interest in doing that.
The UK government mismanaged their borders, and most other aspects of the pandemic; notable exception being vaccination.
Not really, Australia is an continent not an island.
And to be precise, only Europe and Asia are connected by land borders (suez canal, panama canal).
More, UK is an island, also Ireland, Japan... and they don't have much less cases then the rest of the world
The movement of people is a good thing. Hence stamping it out would have a huge cost, both emotionally and financially. The vaccines are comparatively cheap.