The model landed a small role in 2007's St. Trinian's movie and couldn't believe it when she was hired for Terry Gilliam's fantasy epic, opposite Ledger and Christopher Plummer.
She admits she was nervous about taking on such a prominent part in the movie, but found Ledger, who died mid-way through the shoot, to be a great friend and mentor.
She says, "He definitely helped me. From the beginning, he understood that I would be overwhelmed and scared by the size of the project. He encouraged me and said he was really proud of me, constantly fed me support."
Cole reveals she came close to giving up on the film when Ledger was found dead of a prescription drug overdose in January 2008 - a tragedy that halted the shoot.
His role was taken on by three other actors - Jude Law, Colin Farrell and Johnny Depp.
She adds, "Everyone loved Heath. For everyone who knew him, (his death) was devastating. The practicalities of continuing the production were difficult, but it seemed irrelevant.
"Johnny (Depp) slipped seamlessly into the role, but that didn't stop it being bizarre. I thought I was in at the deep end in the beginning - then look what happened!"