The government has released its latest batch of documents covering the potential effects of such a scenario, covering areas like consumer rights, rail transport, copyright and free trade.
On rail transport, the government says it would have to negotiate new arrangements with individual countries to keep trains heading to the continent.
"Arrangements for cross-border services would be subject to any bilateral arrangements that the UK negotiates with individual EU countries," the technical notice said.
Sky News understands work to prepare for such a scenario is already under way, while Brexit Secretary Dominic Raab has said he is confident Britain would be able to negotiate such agreements with the likes of France, Belgium and the Netherlands.
One paper covering copyright reveals Britons could be barred from accessing Netflix, Spotify and other online entertainment while travelling to EU states.
Under EU rules agreed in 2017, citizens can access accounts set up and based in one country while visiting other member states.
"The portability regulation will cease to apply to UK nationals when they travel to the EU," the technical notice said.
"This means online content service providers will not be required or able to offer cross-border access to UK consumers under the EU Regulation.