Please find a link here to the BMFA website, which gives information on the latest news regarding this.
The below paragraph is copied directly from the BMFA website information, so it looks like we are awaiting further detailed guidance from BMFA:
For members of ARPAS-UK, British Model Flying Association (BMFA), Scottish Aeromodellers’ Association (SAA), Large Model Association (LMA) and FPV UK
Members will not need to register as an operator with the CAA system if they are a current member of these associations. With permission [of individual members], the associations will collect the registration fee from members directly and supply their data to the CAA. This will take place initially by 31 January 2020 and an exemption from the need to register will be put in place by 30 November to cover association members until then.
The associations will issue further detailed guidance to their members in due course.