Jersey
Just looked at a short trip trip to Jersey and on UK gov web site we are allowed to travel within the UK without restrictions, but then look on Jersey gov web site and it states that upon arrival you must take a test which is free and self isolate for approx 12 hrs until result is provided, then you are not allowed to leave the island for 72 hrs
It's all a total shambles, and UK mainland is on traffic light system so goes by your postcode you can live in a green area but work in amber or red, but that doesn't matter you can still travel but the opposite way round and it's the same as international travel into UK