That's just Citroen offering a discount called scrappage.
The official scheme hasn't started yet.

It looks like it's cars over £9k with conditions, like you have to have owned the scrapper for a year.

*CITROËN Scrappage & Trade-In Schemes

- Guaranteed £2,000 scrappage cashback for your old car will apply to customers trading in a qualifying vehicle first registered before 1st January 2000 against the purchase of a qualifying new Citroën passenger vehicle (excluding C1, C2, C3, C3 Pluriel, Berlingo First, C3 Picasso, Dispatch and Relay Combi models). To qualify for the cashback, vehicle must be presented with a Certificate of Destruction (C.O.D) provided by an Authorised Treatment Facility (ATF), a V5, valid MOT, be properly insured, legal to be driven on the highway, and have been registered in the customer’s name for a minimum of 1 year.This Guaranteed Cashback is the total value that a customer will receive from the Manufacturer when trading in their qualifying part exchange vehicle for a qualifying new Citroën. Only one claim may be made against each new vehicle purchased.