Hey, my gran has BT PAYG so i had a look @ the readme file:
Thank you for choosing BTopenworld. You should now have a BTopenworld Pay-as-you-go icon on your computer desktop.
Just doubleclick on the icon to connect to the Internet*. When you use this BTopenworld Pay-as-you-go icon you will have the option to launch an additional application (Outlook Express) to send/receive emails by ticking the check box.
To prevent this window popping up everytime you connect, tick the "Dont show this window again" check box. If the window is not being shown and you wish to show it again, right click on the BTopenworld icon in the system tray the next time you are connected with the dialler, and select Show 'Application Select' box.
The next time you connect the Show 'Application Select' box will be shown