I currently have the AEBS wired from the WAN port to one of the ethernet ports on the Sky Hub.
That is the correct connection.
With the AirPort Extreme powered on, hold in the reset button on the back of the device for 9-10 seconds and then release. Allow a full minute for the AirPort Extreme to restart to a slow, blinking amber light.
Click on the AirPort icon at the top of the Mac's screen and wait a few seconds for New AirPort Base Station to appear. Just below that, click directly on AirPort Extreme.
AirPort Setup will open up automatically and take a look at things and suggest a setup. Ignore that and click on Other Options, then select "Create a wireless network". Use any network name that you want, since you will likely turn off the wireless function later.
When the AirPort restarts, open AirPort Utility and click on the amber dot to correct the NAT error. You want to have the AirPort Extreme in Bridge Mode.