With your generous help & advice I am now convinced that it is possible to do a home conversion of a lathe.
Two pieces of software stand out for normal use, cambam to create the toolpath and Mach3 to control the actual business of machining.
I have read the documentation for both bits of software, with an emphasis on Cambam as that's doing the toolpath generation. Unfortunately, cambam does not seem to to me to be able to exploit the full capability of a 3 axis lathe (X,Z and rotation) with a powered spindle. Someone was kind enough to point to CNC wrapper, and that seems to fill part of the gap, but not do it completely.
I use SolidWorks most of the time, so produce 3D models. These I can export as stl format. Now, it strikes me, radial milling is possible on a 3 axis lathe, where the cutter moves up & down as well as in & out as the work is rotated by small increments. This way it's possible to get very intricate 3D models that are not necessarily rotationally symmetrical.
Is there a piece of software capable of doing this, either free or at small cost? Ideally one that can be programmed with axial & radial backlash data.
If not… I have a bit of a job ahead of me.
Regards,
Richard