Current ones are due to expire in 6wks time at end of October-2019.
However if you apply now at the usual place on the RSGB website at http://www.rsgb.org/nov , the new ones will be valid immediately and run until Oct-2020.
146MHz band gets extra year
GB2RS News Team | August 16, 2019
Ofcom has agreed to extend for a further year the Notice of Variation (NoV) for 146-147MHz to encourage radio amateurs to experiment and test new communications schemes and systems.
The current NoVs expire on 31 October 2019. Any Full licence holder may apply for an experimental NoV for the 146-147MHz band: go to http://www.rsgb.org/nov for details. In the last year, 578 NoVs were issued for this segment.