I just started my career with Manchester City on FM12, i signed gerard delofeu (don't know the spelling) at the age of 17, I know that for the Champions League you need 4 players that have to have been at the club for 3 years between the ages of 15 and 21... i asume this means that if i keep Delofeu till he is 21 then he will be classified as a home grown player?
He just needs to be at the club for 3 years BEFORE his 21st birthday (which must be before the 1st Jan that year) to qualify as a home grown player. So essentially when buying foreign youngsters try to work it backwards, look at his age at the point when you sign him, add 3 years, check the date if its before 1st jan or after.
I generally now sign only players who are 17yrs MAX and no older so that i guarrantee they qualify for the home grown player rule in 3 years.
Also, bear in mind that the player has to play in England for the entire duration of the 3years or it wont count (a few months is fine in another country but bear in mind he must have played in ENGLAND for 3years before his 21st birthday).
Try my 17yrs policy and you wont go far wrong.
Also, you dont HAVE to have 4 home grown players for champs league. You can just register TWO or THREE or even NONE. However for each non-regsuietered home grown player you lose 1 registration slot. example, if you have 25players total able to be registered and you only have 3 home grown players, register the 3 players and leave 1 slot unregistered, then you dont have to have 4 home grown players. its not a cheat either, its part of the rules. try it.