Yeah, basically we have to. If other results go our way, then we don't have to win but best to just get the 3 points and not worry about others. In the case of a team finishing 4th in England, that team will have to go through a two-legged play-off round. Whichever opposition that team gets will depend on who comes through the qualifying rounds and how UEFA separate them into 'seeded' and 'unseeded' categories based on UEFA coefficients. The link below might give you a better picture (it's this season CL season qualifying rounds and play-offs). https://en.wikipedia.org/wiki/2012%E2%80%9313_UEFA_Champions_League_qualifying_phase_and_play-off_round#Play-off_round