That link doesn't require you to have internet access, only that you are connected to a BTFon or BTOpenzone hotspot. If the page doesn't come up, it means the hotspot you are connecting to is either off-line or being used heavily, as the hub owner's usage rightly takes priority.
If it is your own hub you are connecting to, then this often doesn't work. Try switching your hub off and refreshing your network list; if you see another BTFon or BTOpenzone signal try connecting to that instead. You may have a number of hot-spots in the area, but as each one transmits the same SSID, you can generally only see the one transmitting the strongest signal, which will most probably be your own.
From September 2001 on BTopenworld Home 500/Home 1000/Home 2000. Then ADSLMax on <n>ildram. Moved to ADSL2+ from ADSL24. I'm now with plusnet. I'm not saying who I work for. Any opinions expressed here are my own.