There is an option to add a cd player to the system it is fitted under the passenger seat cost is £138.94
Blurb from citroen site
This CD player is intended for vehicles which are not fitted with one as standard. Displaying of the tracks on the multifunction touch screen (SMEG) and control via the steering wheel controls (identical to the factory-fitted functions). Fitted under the passenger seat. This accessory requires the purchase of complimentary accessories and the intervention of a specialized technician. Contact your dealer.
I ordered a CD, cost included in the price of the car, and when I cancelled the order after finding out it went under the passenger seat I was refunded £300, so it potentially could cost you that much. Apparently on the continent the CD goes in (and completely fills) the glove box.