I think everyone’s got the CAD/3D programs covered, so a slightly “out there” answer:
If you’re just doing 2D blueprints for yourself, do you actually just need a 2D vector program for doing a scale drawing with measurements?
I’ve done a lot of floorplans / layouts/ site maps etc using Inkscape, for instance.
It depends on exactly what you’re wanting out the other end - so you may be lacking a lot of the features in a full CAD program, but the learning curve is comparatively so shallow that you might have a working plan by the end of the day, rather than the end of the month.
“I’m so furious with their absolute incompetence, I’m going to cross out ‘best wishes’ and simply write ‘regards’ at the end of this email”
*20 minutes later*
“WHAT HAVE I DONE! I AM A MONSTER!”