Almost all channels, available from the satellites which beam Sky signals to earth, can be accessed simply by entering the relevant number into the electronic programme guide. (The only exceptions are a few channels which are used by 'instore' radio systems, such as in McColl's convenience stores or Topp's Tiles. You need to manually enter the required information if you really want to listen to the rubbish which they broadcast).
See here for a list of what's available:
http://www.wickonline.com/fta.htm
Chris