After a long struggle, I am finally at the end game. From the across clues, I have the following letter changes:-
23: G for C
18: not applicable
17: U for O
12: S for I
30: E for L
32: not applicable
33: don't know
31: E for C
19: U for A
22: not applicable
21: S for A
14: don't know
1: E for T
11: not applicable
13: Z for R
27: + for &
I trust that the foregoing is not too specific for this site, in which case would somebody be kind enough to confirm whether any or all of these are correct and perhaps add the letters for 33 and 14 for me.