I can, but I'm not a driver.
Only Hitchin and Kings Cross drivers sign Moorgate now. (I believe there may be restrictions on how far north those drivers go too, but I'm not certain). However, Hitchin and Kings Cross drivers are able to drive anything, really, presuming they are stock trained.
Occasionally a Cambridge or Peterborough driver turns up on a Moorgate service, but then finds no relief at Finsbury Park, so the train is cancelled, because the driver can't go down the NCL.
There are also new depots at Welwyn Garden City and Hornsey. At the moment the WGC depot is just a separate link on the Hitchin roster, ready to move when the depot is built. I believe this is for drivers to drive the WGC-Maidstone and WGC-Moorgate, but I stand to be corrected. As for Hornsey depot, I don't know much about that at all.
As I say, I'm not a driver, but I do speak to a lot of them. There are GN drivers on here, so I'm sure one will be along soon to say I'm talking rubbish!