Guidance was always in place in the EU for a Grace Period (GP). However, it is always up to the member states (MS) to follow a guidance. The MHRA has applied GPs but commits itself now with a solid process. Other countries have given GPs. Among them Germany, Switzerland, etc.
MDSS as the EC REP has applied on behalf of a client with its Competent Authority (CA). This allowed the client to sell his products without a NB certificate for a defined period. For manufacturers outside the EU it is important to know that the relevant authority is the authority of the EC REP – not the authority of the NB. It is not a trivial process and requires some negotiation skills!
With the conditions, it is an individual process, which also takes resources away from the MDR implementation. The good news is that you will be able to sell the product EU wide.
Contrary to this, article 59 MDR or article 11 (13) MDD allows MS to permit the selling restricted to their territory.
The big questions is what happens in terms of the Brexit. The MHRA GP may only last until the end of 2020 if there is not a trade agreement covering this aspect.
Here the MHRA reference.