GB-PVR doesn't come with icons for any of the TV channels, you have to assemble those yourself. I got a bunch from LyngSat Logo, a pretty awesome resource for creating a collection of station logo icons. You need to put the icons in the proper directory - mine is D:\GB-pvr\media\ChannelLogos but I think if you used the default install directory for GB-PVR, it would be something like: C:\Program Files\devnz\gbpvr\media\ChannelLogos. Anyway, you also need a text file named TV Channels List.txt that associates each icon with a station number. The entries follow this template:
CFCN 3 CFCN - where channel 3 is associated with a file called 3 CFCN.jpg.

Here's my collection of icons for Shaw Calgary, it's not complete but it has most of the analogue channels that you can record with a tuner card. The ABC logo is a bit lame with the blue background, I should change that. My TV Channels List.txt is in there too.

StationIcons.rar