is a cv joint hard to fix?

no

The usual fix is to replace the drive axle. You don't mention make, model or year, but generally it is a medium DIY job. In all cars the axle nut has to be removed, and that is usually insanely hard without an impact wrench, insanely easy with one. In many cars the tie rod end has to be popped out, which is also much easier with the proper tool.

A warning - even for a single model and year there are often several versions of drive axle. They are usually different on the left and right sides, they may come in ABS and non-ABS versions, and sometimes you will just be given the wrong one altogether. When the old axle is removed you should place the new one alongside it to verify they look the same and are the same length... otherwise you will be writing the next question in crayon because the orderlies won't let you have anything sharp.

not if you have the right tools. easy as doing your brakes just a little more to take off