Building layout - 2D - Converting hand sketches to CAD drawings

Occasionally we are asked to produce plans to show how equipment/machinery will fit into a space. We are provided with a PDF of the architectural plans and then mark-up by hand where we best think equipment should be placed. We require someone to convert our hand sketches/notes into a presentable CAD/PDF format - basically modified plans.
As this will be an iterative process - bouncing design and notes too and fro, we will requires someone who can respond quickly - so UK time zone work day availability would be advantageous.
Experience with 3D rendering of spaces could be useful - presently outside the scope of this brief but I could see our client asking if we could produce these at a future date.
While this is a small amount of work I could see this becoming a regular requirement.