Your real problem is not the NAA it’s our own lovely CAA who have advertised a deadline here:
https://info.caa.co.uk/eu-exit/commercial-pilots/
where they won’t guarantee to complete the process on time unless they have had the request from the NAA by 1st Jan, so I would be inclined to get on with it if I were you (especially if you want to fly non G-Reg)