Under current UK COVID-19 restrictions, you must stay at home. You must not leave home or travel, including internationally, unless you have a legally permitted reason to do so. Check the rules that apply to you in England, Scotland, Wales and Northern Ireland.
From 4am on 18 January, if you intend to travel to England, Scotland, or Wales, including UK nationals returning home from travel abroad, you must provide evidence of a negative COVID-19 test result taken up to 3 days before departure. If you do not comply (and you do not have a valid exemption) your airline or carrier may refuse you boarding and/or you may be fined on arrival. All other current entry requirements and restrictions continue to apply.
If you are legally permitted to travel, check our advice for the country you are visiting. Some other countries have closed borders, and may further restrict movement or bring in new rules including testing requirements with little warning. Before you return to the UK you must provide your journey and contact details. Also check if you need to self-isolate.