While certainly a very personal thing; I recommend that you work as much as you can.
Establishing a routine and keeping your brain active can help increase you energy levels. Your appetite will increase because your using your brain and body.
It can also help your mental health. Getting out of the house and away from your dialysis machine and the reminders of how ill you are. It will also give you a brighter outlook on your future.
I recommend informing your work as soon as you become aware that you have CKD. Your dialysis unit/hospital should have information written especially for employers or if not get them informed of how serious CKD is.
After each of your appointments, keep your employer updated with as much info as you can/willing.
The law offers you some protection in the form of the Equality Act 2010. It protects disabled people from discrimination in the workspace. The law defines someone with a disability as;
A person (P) has a disability if—
(a)P has a physical or mental impairment, and
(b)the impairment has a substantial and long-term adverse effect on P's ability to carry out normal day-to-day activities.
The Act is quite long winded but it confirms that workplaces have to make reasonable adjustments. What counters as a reasonable adjustment is up for judicial interpretation. A copy of the full act can be found here.