Please Please help me regarding chimney recess install

In a new extension we will be having a chimney stack built specifically to mount our 40" lcd. The lcd is arounf 11cm thick, my builder is asking me how deep the recess is to be. I would love the screen to be flat inline with the brickwork. How deep do you guys advise and is there a bracket available that can be adjusted (ie pulling the tv forward)

Many thanks