End of the Line was a story by Steve Parkhouse and Dave Gibbons which ran in Doctor Who Monthly #54-55 in 1981. In it, the Doctor arrives in what seems to be a London Underground station somewhere in the far future — a time when most members of the human race have devolved into savage cannibals. A small group of normal humans, the Angels, are trying to escape to a mythical place called "Countryside" at the end of the Tube line. The Doctor helps them get their train moving, but is separated from them and, having travelled outside the city by TARDIS, finds that the countryside is a toxic wasteland. The Angels seemingly never make it out there anyway.
This story was apparently the inspiration for the 2007 TV episode Utopia, which basically has the same plot but with spaceships instead of Tube trains, and the addition of the Master. It has no connection to the story End of the Line, which ran in Misty in 1978.