How do you operate the headlight washers, and are they behind the small looking flap that's along-side the small fog/turning lights.

They are washed when you wash the screen if the headlights are on then every tenth squirt,

From the manual....

Headlight cleaning system
 Read and observe     and     on page 76 first.
Headlights are cleaned under the following conditions.
 The ignition is switched on.
 The low beam is switched on.
 The outside temperature is about -12° C to +39° C.
To clean the headlights, the headlamp is also sprayed after every ten squirts. The adjustment of the spray interval can be adjusted by a specialist garage (maximum after every twentieth spraying of the windscreen).
To ensure the correct functioning of the system, even in winter, this needs to be regularly cleared of snow and ice (e.g. using the de-icing spray).