UK Common Travel Area
As part of the UK Common Travel Area, the Channel Islands are classified as domestic travel (not international or global travel) when travelling from the United Kingdom.
However, it is important to note, that similar to England, Scotland, Wales and Northern Ireland, Jersey and Guernsey have their own independent Governments and as such it is essential to be aware of the latest regulations in the destination jurisdiction.

Travelling to the Bailiwick of Jersey 

Jersey - Wikipedia

Covid-19 Travel Information

With effect from Monday 7th February the Government of Jersey suspended all the current requirements under the Jersey Safer Travel Policy, but as this will remain under review please check, for the latest information.

Travelling to the Bailiwick of Guernsey

Flag of Guernsey - Wikipedia

Covid-19 Guernsey Travel Update
With effect from Thursday 17th February 2022, all requirements under the Safer Travel Policy to Guernsey will be suspended.  Any passengers arriving into Guernsey on or after 17/02/2022 do not need to complete the Travel Tracker or undergo testing or isolate on arrival.
Please keep up to date with the latest information for Guernsey

Freedom Holidays - Covid Refund Guarantee 
In these uncertain times, it is reassuring to know that if you are unable to travel or to take your holiday because of a national, local and Island lockdown, that Freedom Holidays will guarantee that you will get the option to defer your holiday or receive a full accommodation refund. Please note that the refund applies only to your booking accommodation payment(s) and only when the lockdown coincides with the period of your booking. 
The refund guarantee covers national, local and Island lockdowns, but does NOT cover you (or members of your party) for being unable to travel because you (or a member of your party) fall ill with Covid, or are required to quarantine, self-isolate or shield due to illness or disruption to travel arrangements. These events can be covered by you taking out travel insurance. There are a number of policies that include cover for illness with Covid and self-isolation (example links below), and some Bank/Building Societies annual travel policies also cover this. 
Alternatively, you can look for suitable cover on websites such as GoCompare, CoverwiseAllianz AssistanceTrailfinders
Freedom Holidays are not selling, promoting, endorsing or recommending any particular insurance product, and do not benefit financially from, nor have any formal relationship with, any of these providers. 

"Updated as at 15/02/2022"