Holman was signed from AZ Alkmaar by Lambert's predecessor Alex McLeish.
Lambert said: "If there is one lad who has probably got a bit of trepidation, then it would be Brett because it wasn't me who brought him to the club.
"But I have spoken to him to reassure him and he will get a right fair chance.
"I don't know much about him but I have watched some of his games. He did well at Alkmaar so I don't have any worries about him on that score.
"It's not as if you are going in with a young kid. He is 28.
"As long as he works hard and tries to be successful, then he will be the same as everybody. He will get a chance."