The Premier League normally sends its top four clubs to the Champions League group round. However, if they do finish in the top four, or if champions elect City capture the trophy, the fifth-placed team will be eligible for a berth in the competition. They will go into the draw along with the other fourth-place teams.
Currently, Sheffield United are the only non-top-four club left in the Premier League. They were relegated from the top flight last season after 67 years of existence.
However, they were reprieved from the drop when Aston Villa and Blackburn Rovers failed health tests on their stadium grounds. The two clubs were ordered to play their next three matches at other venues -- three for each side -- while their respective stadiums are repaired or replaced. This means that United will remain in the league this season. More details on that story here: https://www'thepremierleague.com/news/sheffield-united-remain-in-the-premier-league-this-season-37000/.
Finally, it should be noted that since the Premier League was first founded in 1992, only three non-top-four teams have qualified for the group stage: Southampton (2008), West Bromwich Albion (2013), and Hull City (2014).
However, if they finish fifth, they will join the top four in the competition the next season. "Should a Premier League team win the UEFA Champions League, they will automatically qualify for the group stage of next season's competition regardless of their league finishing place," the Premier League stated.
The statement further noted that if a Champions League winner finishes below fourth place, they would be required to play a two-legged playoff against the team who finishes third.
It is important to note that although winning the Champions League is regarded as one of the most prestigious victories in football, it does not guarantee future success. In fact, only three Champions League winners have gone on to win the following year's European Cup: Liverpool, Milan and Real Madrid.
The other two winners were Anderlecht in 1995 and Juventus in 2003. Both teams were relegated the following season.
Furthermore, there are no guarantees that if a Premier League team wins the Champions League, they will retain their title. Since the inception of the Premier League in 1992, only Chelsea has been able to defend its title. The others teams have been beaten by previous champions after losing out in the semi-finals or final.
In addition, since the introduction of the Premier League Cup in 1955, only Manchester United has been able to successfully defend this trophy.
The top four clubs in the Premier League will qualify for the Champions League group stages, while winning any of Europe's championships will also guarantee a spot in the group stage. The Champions League allows for a maximum of five English teams to compete. If more than five teams qualify, places are allocated by ranking highest to lowest based on how many points each team scored during the season. If still more than five teams qualify, leagues or groups are split up to allow as many teams as possible to participate.
In addition to the four English teams, other non-EU teams can also qualify for the group stages. These teams must win either an invitation cup competition or the right to enter the qualifying round of the Champions League play-off system. The number of non-EU teams has been limited since the start of the current UEFA financial fair play regulations. Starting with the 2013/14 season, only one non-EU team can join the four English teams in the group stages.
Non-qualifying European teams that finish in the top three of their league will also receive a place in the next season's Europa League. This is called "play-offs". In this case, the four Premier League clubs that do not qualify for the Champions League will be matched against the third-place club from the Bundesliga and the winner will take their place.
If a Premier League team wins the UEFA Europa League, they will automatically qualify for the group stage of the UEFA Champions League the following season, regardless of their league place. A maximum of five Premier League teams can qualify for the UEFA Champions League. If more than five teams qualify, those not entering at the qualifying round stage will drop down to the UEFA Europa League.
In other words, the winners of Europe's second-tier club tournament go straight into the Champions League. The Europa League champions must be ranked between third and sixth in order to secure a spot in the next season's Champions League. If no European club is ranked among the top six nations by revenue, then the spot will be given to the highest-ranked club from outside Europe.
Runners-up Europes leagues clubs contest a one-off match to determine which side goes into the other competition. If the rankings are equal after this game, then a series of tiebreakers based on how many points each team scored during the Europa League campaign would need to be played out before deciding who qualifies. For example, if both teams scored exactly the same number of goals during the tournament, then extra time would be used to decide the winner. If still tied after that, a penalty shoot-out would be taken place to determine the final result.
The last English team to win the Europa League was Chelsea in 2012.