A little bit of heat on the fixed nut may be enough to slacken the bolt, however the bolt may be seized on the bush sleeve, which you can easily replace if you damage it during the dismantling.
You have to remove the drive shaft to remove the knuckle, but that is not a big job.
Just remove the split pin and loosen off the drive shaft nut before you get the car in the air.
If you do not have a very powerful impact wrench and if the nut is very tight, use a 1x metre heavy duty breaker bar and a piece of scaffolding pipe if extra tight.
It is a normal R/H thread.