Good CAM software is not inexpensive - typically a lot more expensive than say AutoCAD. You also have to know the specific CNC machine and the type/model of controller fitted to it so that the code is compatible. You might wish to contact your local polytechnic/training organisation or speak to an existing user who might as a gesture of goodwill or modest fee create the code for you. How to Convert DXF to G-code: 4 Easy Ways by Jackson O'Connell Updated Converting from DXF to G-code is useful for getting your CNC model cut just right.
It is common to be able to download a limited time version of some software but in the CAM area the limit is often that it will not produce G & M code output, but you can learn the software and see the toolpaths on the screen. A users usually has to have a good understanding of machining processes, tooling etc. It usually has a significant training and support component/requirement as well. Ace Converter - Free program from DAK engineering to convert 2D DXF files into.
As you have found free software usually has limitations (as you might expect) as CAM software is not easy to write and goes to a limited, critical, demanding market. First stage : read in the dxf and output g-code, oke this works for line.