This reply is aimed towards Andyev.

Did you manage to resolve this problem as I am in exactly the same position to you?

I am aware that Sky requires pppoa rather than pppoe (see settings below), but do not know how I use this information to configure the AirPort.

Any help would be appreciated.

Richard

Protocol/Encapsulation :- PPPoA (PPP over ATM)
Multiplexing method: VC-BASED or VC-Mux
(On some routers the above 2 settings may be combined as "PPPoA VC-Mux".)
VPI = 0
VCI = 38
DSL Standard: G.dmt
Security Protocol: CHAP

there's nothing out of the ordinary you need to do on the airport.

go to the "internet" tab in airport utility.

<connection>
connection using PPPoE
enter your username
enter your password
enter your password again
leave service name blank

<PPPoE>
Always On