That is A LOT of black patent. I would use mostly Roasted barley, and a touch of black patent. Maybe 1lb R.B. and maybe 4-5 oz of black.
Cut down the Crystal as well. Maybe 3/4-1 pound. If you want some more body, add some flaked barley.
Infact, as you are adding lactose as well, maybe keep the Crystal even lower.
Nor sure about how much coffee or lactose to use though.....sorry!