There definitely is no embargo on contractors who have flown for the company, if anything I would say you would probably be top of the que if you applied.
Just to respond to the posts above re career and southish bases etc, I don't even know if I will be here in 10 years so I don't want to come across as too much of a saleswoman but let me say two things I believe based on nothing more than instinct
Two things will happen:
LGW will be a J2 base
Long haul is less than 3 years away, with Air Tanker flying the initial season to handle all of the initial risk.
Remember, the company have 70+ Airbus on order, nowhere does it say the aircraft are exclusively A321... And many of our cabin crew and engineers are now A330 qualified...