Assuming city win the fa cup and with us winning the league cup, does that mean an extra 2 Europa places go to teams based on finishing high enough up the league? If so, that means 8th place finish goes into that conference tourno. I think. Watch Utd spawn a Europa spot on Sunday.
England gets 7 places, not 8. Additional places can be earned in some instances through winning European competitions but no English team has done that this season. At the start of the season, these places are distributed as follows:
1st-4th = CL
5th = EL
FA Cup winners = EL
League Cup winners = ECL
If the cups are won by teams who have qualified for Europe through their league position then those places get handed down to the league. Since we have qualified for the CL, the ECL place we earned by winning the League Cup currently goes to the 6th place team in the league.
Should Man City win the FA Cup, the EL place they earn by winning it will pass to the league, meaning the 6th place team now qualifies for the EL and the 7th place team now qualifies for the ECL. Should United win it they will qualify for the EL and, since they won't qualify for Europe by league position barring a highly unlikely set of results on the last day, the place will not pass on to the league.
So the possible scenarios are:
City win the FA Cup:
6th place = EL
7th place = ECL
United win the FA Cup:
6th place = ECL
7th place = Not in Europe