Thanks for the offer, but I've reverted to my librecad, which is fully functional and does file conversion as well as export and import dxf files.
It just not as easy to use without a graphics pad. Plus my old lenovo laptop isn't the quickest any more, originally on XP PRO, I upgraded the memory and the software to Windows 10.
I've got a 64bit compaq laptop on Windows 10 Pro but it has a power fault, which I can't trace.
Must try to find a laptop engineer who doesn't charge the earth to fix it.
But I'll manage for now, it keeps me occupied trying different ways of working.