Training Matrix Help Please!!

Afternoon

Please could someone help me here with my training matrix.

I currenlty have it set up to remind me 30 days before a quallification is due to expire using conditional formatting. Next to each date i have an IF formula to tell me if it is current, renew, expired.

The formula i am using is as follows:

=IF(C10<TODAY(),"Expired", IF(C10-30<TODAY(),"Renew", "Current"))

What i would like it to do is instead of saying expired all the time, if the box is left empty that it Says N.A

Also i require a conditional formatting formula to make the boxes go Grey if they are empty, but am unsure of the code.

I have attached my training matrix to this for you to see more clearly what i am trying to achive.
Thanks

Carl