It is possible to do PCBs on this sort of set up but it is not easy to get good results.
The workflow I have used is KiCad -> Gerber -> Rapid-pcb.com -> Gcode -> LinuxCNC. I have also tried Flatcam but had some problems setting it up on a mac. There is quite an well featured ULP for Eagle that does PCB->GCode directly so you could bring your board into Eagle and then export the GCode once you had done all the proper design work using KiCad 
Some of the problems you might find are;
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Board is never flat! There are a variety of auto leveller solutions which probe the board first to produce a contour map and offset the gcode to allow for the unevenness. Isolation cuts of 0.1mm are all that is needed but if part of the board is low you may not cut an isolation track and if too high you may not have any track left! Vacuum tables help but you still need to level.
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You don’t have a solder mask - SMT component placement is possible but not easy. 1206 is doable, not tried anything smaller.
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Two sided boards need a mounting jig to ensure alignment.
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You need a very high speed spindle and good dust removal.
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I am not sure the gantry you picture would be sufficiently rigid for milling board out unless you were very careful with your step-down.
I have seen people advocating using this sort of setup to use a sharp point to score through a resist (e.g. permanent felt tip drawn over the copper) and then etch. (you then have all the mess of etching and the problem of aligning the drilling).
On the plus side, you have the board in your hand in a very short time.