Hi Gavin,
When we state that we will work with several SSIDs it is becasue you will link each SSID to an specifc VLAN, each VLAN to an specific subnet or broadcast domain and on each SSID you will use a diufferent security method.
Now since you will be working with different SSIDs each linked to the same subnet it would not make sense becasue at the end both SSIDs are on the same subnet or broadcast domain which is the same as having one SSID.
The access point allows you to configure several SSIDs with out using VLANs but you will need to use the same security method on both, and this could be configured via the CLI but not the GUI since the GUI will give you an error saying that you need to work with VLANs and link each SSID to an specifc VLAN.
Check on the follwoing link to understand VLANS on access points.
