Your Atlantic is equipped with 2 USB ports and 1 socket. These can be found underneath the display. You might find an additional USB port on the upper bed.
The USB ports can be used if you have enough power on the leisure battery but the socket only works if the van is charging/plugged into a mains supply.
Note: In case you have the display below, with a clickable 12V button, it needs to be ON to use the USB ports.
You'll know the 12V button is ON if there is a blue light on it.
Other relevant articles:
How to charge the leisure battery