GTI - Engine smoke & judder

[S.Kayani]

any ideas what it could be?
there was a small tweeting noise at first, when it was checked, the first spark plug was making the noise and stopped when pressed down.

now the car is making a louder noise and smoke it coming out of the back... it is also juddering....
any ideas on what it could be? and the cost?

just dropped it off at local garage