If you are a British national, then you can no longer apply for an EHIC, as the UK is no longer part of the EU. The UK Global Health Insurance Card (GHIC) is a replacement and lets you get state healthcare in Europe at a reduced cost or sometimes for free.
The GHIC is valid in the European Union: Austria, Belgium, Bulgaria, Croatia, Republic of Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, and Sweden.
Please note you can use a UK passport to get medically necessary healthcare in Norway (for example, emergency treatment or to treat a pre-existing condition).
To apply for a GHIC click here.
Your GHIC covers you for emergency medical treatment only, including treatment of a chronic or pre-existing medical condition that becomes necessary during your visit. It can also cover oxygen and kidney dialysis, but you will need to pre-book these treatments before you depart for your trip. It will not cover your medical treatment if you're travelling abroad specifically to have medical treatment, including giving birth.
The gov.uk website recommends all UK travellers to take out an appropriate travel insurance policy when travelling abroad. It is important to remember that an EHIC or GHIC does not cover you for rescue or repatriation costs or if you are on a cruise. It's also important to remember that each EU country's healthcare system is different, and without insurance, you may have to contribute to some of the cost of your care – like locals do.