CatMan: I think I read, that you will fly (upgraded) UA business to London - don't you?

On those international flights, just showing your (upgraded) business class ticket (you don't need an entrance voucher), you have automatically access to UA's Red Carpet Clubs at the american gateway airport and in London Heathrow. Enjoy!

But you can't use UA's Arrival by United service on upgraded business class tickets - don't shoot the messanger.