Thanks to Muraria and drxx I persevered with this and have now returned to find I still have not worked out the first four letters for 22a because I cannot solve both 15d and 17d. I know it’s a long shot because you will all be at Wimbledon, but please will someone help me?
15d: Prepare to work at paper (paired with 17d: reportedly half bring stick in the mud for writing.
I have ?O?O and DE??
I might have something wrong so humour me….
22a: I have ????VIRI