How familiar are you with engineering drawing, CAD is not too difficult to use and learn if you have some engineering drawing experience.
I use CAD reasonably often and have never done any formal course other than engineering drawing back in my schooldays before computers were yet to appear, once you have mastered the basic drawing commands it is very to advance and develop you own style of drawing and command inputs
My old business partner got into CAD and taught himself from scratch with some previous drawing and draughting knowledge and we even purchased a couple of large format plotters to print off as fitted drawings for jobs we had completed, he was asked by one of our customers (local hospital trust) to advise them on going digital for all the drawing plans they had, quite a few of the engineering staff were starting a CAD course at the local college and being self taught my business partner thought it might be a good idea if he went thinking he might learn something he didn't already know aside from teaching the lecturer some different methods and a few bit he didn't know he completed all the workbooks of a 12 week course in four and a half of the three hour weekly sessions
One tip I would give you is draw full size and only scale the drawing when printing