I've tried Eagle PCB and works fine for small PCB's, but I think that you must be sure that the software you use provides a G code output. PCB CAM files are usually in "Gerber code", this is a very particular code because PCB manufacturing, even in small batches or prototypes can have several layers and different ways of manufacturing, for example, a PCB CAD software creates one file for tracks and a separate file for drilling, they also create other files for solder masks, printing layers, etc.
If your PCB has only one layer use the bottom layer, if you plan to make a two sided PCB be sure to add alignment holes in order to make both layers coincide when you turn over you PCB once the first layer is finished.
A friend of mine has made a few PCB's using Eagle's Gerber CAM output files and he told me that they are basically equivalent to a regular G code's CAM file but some tinkering with the code is in order: you have to manually add the Z movements, define both spindle and axis speed based on your best knowledge of tool and material and add tool change code lines. He uses very small carbide cutting tools, 0.5mm and 0.2 mm. I think that Eagle's file makes 90% of the job and the 10% left is to be solved by the expertise of the machinist.
Good luck with your PCB's