Originally Posted by
PTahCha
You are correct if this was on a domestic itinerary.
However, since OP is based out of LHR, their international travel would allow them to have access to the UC, assuming the question is related to LHR-US travel solely.
That is true for revenue tickets, but I had been previously told that UA would not "bill itself" for non-rev lounge access. But personally I have only done this with *A status.