Thanks to your help I've now finished, but there are several that I don't fully undertsand (or may have got wrong!) Could anyone provide explanations, please?
13ac Pick a quiet moment - I have APPOINT
20dn Country in Central America, country in Asia, and one midway?
I have ROMANIA (I can see OMAN, but don't get the rest)
(I was also going to ask about 4ac, but I've just worked it out)