FJJP
Your profile puts you in the UK, so I will pass on some information I was given by our SysAdmin last night, unfiltered and unchecked:
In order to attach to WiFi in M'Way service stations, airports and the like you have to have an account with BT. I believe that they are the only suppliers. They will give you the appropriate encryption key.
However, WARNING:
They charge a cool £1 a minute anytime you are in range whether you use the connection or not with a minimum connection time of one minute.
That means that if you have your device switched on in an airport you can receive a massive bill, and if it is on in the car you could pay £1 toll every time you pass a service station.
I say again, I don't know that the above is true, but our SysAdmin is usually well informed.
My advice is to get a GPRS account and a BlueTooth card, which works brilliantly well for me.
Timothy