A scenario in which the United Kingdom leaves the EU without agreement remains unlikely, given the mutual interests of the United Kingdom and the EU in securing a result for the negotiations.
However, the British government is preparing for all eventualities, since, to date, there is no certainty about the outcome of the negotiations.
So a series of technical notes have been published that provide information that allows businesses and citizens to understand what they should do in a "non-agreement" scenario, so that the same subjects can make their preparations.
At this link there is a guide of great interest for the Industry:
Trading goods regulated under the 'New Approach' if there's no Brexit deal
As it covers all product legislation to regulate the placing on the market of products and affix the CE marking.
The following passage is particularly interesting:
"The existing harmonized standards (used to demonstrate compliance with the essential EU requirements) will become the" designated standards "of the United Kingdom, used to demonstrate compliance with the essential requirements of the United Kingdom .As noted above, immediately after exit, these will be identical to the essential EU requirements. "