Oh, I'm so glad you said that, GK. I'd reached the same point myself, but I thought I was just being pernickety or dim!
What we have for each clue is an unknown letter + wordplay (but no relevant definition, only a misleading one), leading to a word of undefined length. In what way does this resemble a cryptic crossword clue?
I know I could try to identify all the definitions and consider all the lengths in the grid, but I really can't be bothered.
Having already expended some mental effort trying to solve all the clues WITHOUT the special instructions (a meaningless waste of time - thanks, Grauniad), the clues are contaminated for me anyway, IYKWIM.
I did run through them quickly with the special instructions in mind, but cannot get anywhere and, like you, resent putting in so much effort.
This printout will become a shopping list in a minute, and I'll go out and do something more useful with my time. Enjoy your book!