If what you are feeling is "tired all the time", then that is indeed normal.
All you can do, as you say that this is an important project, is soldier on as best you can for the next 2 weeks.
Have a sleep, or at least rest as much as you can over the next 2 weeks.
Go to bed for a nap as soon as you get home, or crash to bed early every night.
Once you have had your operation, you will be really tired for a few weeks, and will need plenty of rest, so try to get as much time away from work as you can.
Gradually your energy levels will improve, but give yourself TIME to heal.
In 3 months, you will be feeling so much better.
In 6 months you will be feeling really great
See you on the other side