Once you've removed your turkey (and are resting it), simply use the same pan with all the juices and drippings and leave on the stove top. Using a ladle, try and skim off us much fat as you can first.
In a cup, mix you milk and flour (this is to thicken your gravy and by mixing the flour with milk first, you avoid those horrible lumps of flour if you added it straight in dry)
On a medium heat, add in the chicken stock and milk-flour mix gradually, stirring it in to the leftover drippings.Bring to a boil; cook and stir for 2 minutes or until thickened. (It will be your personal judgement on how thick you would like your gravy so it's important to add the milk-flour mix and stock slowly so you can gauge it.