The singer and rapper revealed that he hasn't has time to finish the record - which is out on July 14 - due to commitments to his directorial debut.
Watch what he had to say below:
He said: "There's so much work to do on this film - I still haven't finished the soundtrack, which is supposed to be coming out July 14.
"I've got a couple more weeks do that and I'm finding it extremely difficult."
On his next record Ballad of Belmarsh, he explained: "Ballad of Belmarsh is supposed to be the hip-hop instalment of the Strickland Banks saga. I tried to get it out before this film came out and it was just impossible."
The star admitted that getting Ray Winstone to feature on one of the LP's songs was his "proudest musical moment," adding: "After this I need a break. I need to evaluate what it really is I want to do next, but it will see the light of day."
Plan B releases his new single 'Lost My Way' on July 2. Listen to the track in full below: