Im not an aircrewman but I sit next to them.
Keep working on the Nav. You must be able to do S/T/D in your head. But above all work on the Maths. Maths, Maths, Maths.....
CAMB is fairly straightforward. You stand there, get poked and proded...cough a little, bend over and smile...breath into this, listen to this, can you see this....
If your fit and healthy (hope so as a Booty) then you should have no problems