Congratulations Jo. I am very pleased that you stuck it out and completed your CELTA course. Gradings for CELTA I think are - A,B,Pass. I have never met anyone who got an "A", but just under one-third of my course members got a "B". I would not feel disheartened if you got a 'Pass' as this is fine. Most employers don't ask for any particular grade. If they are competent employers they will want to know what your trainers stated in your reference. Grades might be important if you wanted to continue you studies with the DELTA, but experience will be the key factor. (If you haven't got a reference then ask for one).

Just think of the grammar aspects as a journey. Use Swan's Practical English Usage as your guide to proper form and meaning, but more importantly, "usage."

Two books I enjoyed (yes, I'm a masochist), are Eats Shoots and Leaves: the zero tolerance approach to punctuation by Lynne Truss - , and also the parody of this book, Eats Shites and Leaves: crap English and how to use it. by A. Parody. The latter has some interesting stuff and many examples of bad writing that I have adapted for students to analyse as part of their writing assignments. I liked the 'Language Doctor' pages, with some patient notes from the medical profession. Some examples that made me laugh and with my comments [appended] :-

Patient has two teenage children, but no other abnormalities.[priceless]
The patient states there is a burning pain in his penis which goes to his feet. [lucky man]
She has had no rigours or shaking chills, but her husband states she was very hot in bed last night.[alas, the earth did not move]

Good luck with the job search.

CL