Ok, a few things here - I'm going to assume your V6's internet connection is not the underlying issue and probably live to regret that.
In your TV guide, does the programme you're clicking on, say "Watch from CatchUp" or "Goto CatchUp"? Sometimes in the immediate few hours after broadcast before the EPG has been updated, it will say "Goto" and you'll have to find the programme manually.
If you follow Home > CatchUp > Channels > BBC iPlayer, does the app load that way?
As a quick test of your box's internet connection, can you play VOD from any other channel? Pick something on CatchUp from ITV, C4 or C5 and see if they play ok?
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks