Thank you Judygs and Mamya
Of course once I got 20ac, I immediately got 21d and 13d, which gave me enough letters to get 23,15 and then 6d. I now have all the letters for 16d, and a possible answer. I just have to work out why it is correct!
Just two left - 22ac and 22d. Again some hints would be helpful. Then I can put it aside and watch telly in peace.