Not sure of two of the 4-letter clues - always find them tricky!
12 down - Tons, a number lifted - such a weight! (4) N?T?
29 across - First book, English, that may be passed to child (4) ?E?E
Also 42 down - have lots of letters but not seeing it. Vehicle with bread rolls left out heads for kitchen (8) ?A?G?G?S