Finally got the USB WiFi adapter working
I disabled the built in WiFi by adding 'dt-overlay=pi3-disable-wifi' in /boot/config.txt, which then made the USB dongle wlan0
However I was not able to connect to the WiFi AP, as I could not obtain an IP address, so had to do the following as well
I had to disable the virtual interface by changing KERNEL==""phy0" to "phy1" so that it did not bind to the USB dongle
I then changed the interface in /etc/dnsmasq.conf to wlan0.
I can now connect to the AP and log into Moodlebox on the Raspberry Pi
I obviously don't know if you have come across this before but, on boot, I see an error [FAILED] Failed to start dnsmasq, although this is actually working as it is shown as active when using 'systemctl status dnsmasq.service'
The error was also being reported when using the internal WiFi before I added the USB dongle
I am running Moodlebox an a Raspberry pi 4 B
Thank you for you help