It would be very unusual for the AAIB to issue either an Initial or Interim Report other than in the case of a fatal accident (for example the Bond Super Puma) or a complex investigation (such as BAW38).
All true except where there is an immediate safety interest beyond the affected parties as demonstrated in the case of multiple pages on PPRUNE !
Perhaps somebody should send an E-mail to the AAIB asking for a prelim summary before their next rostered flight.