I did all mine in one day at the local DVLA office - they give you the VED disk straight away and the documentation necessary to get new plate made up - they don't take the old VED back so nothing changes initially.

With two VED disks in your possession you can choose when to get/fit the new plates. I notified my insurers by phone as soon as I'd switched plates. Mine was parked on private property at the time - if it's parked on the highway it's more complicated but that''s largely theoretical.

The plate authorisation runs out after a month, I think but by then the new V5C should be with you.

Logically, there must be links between the old and new numbers as DVLA don't know the actual date of the switch. In my case the DVLA vehicle check took longer to show the change than the MID insurance database - a couple of weeks compared to a couple of days.

There is a risk that ANPR might flag you up for a stop but since you've got all the relevent documentation for the police it's not an issue. Presumably ANPR uses the same database as the DVLA vehicle check so the new number may not appear for a couple of weeks.

how did you stand legally with not having a tax disc to display? I am about to put the number plates on the car I drive on retention but I need to still use the car and as I understand it even if a vehicle is legally taxed and shown on the database as being taxed its still an offence to not display a tax disc unless thats changed