I enjoyed this, thanks to Brockwell.
Found it difficult, but that may have been fatigue because I just got back from a concert.
I think 4 and 18 are the 2 UK-specific clues. I got 4 fairly quickly from wordplay and faint geographical memory. 18 I wrote in quickly, but couldn't parse until long after the grid was complete due to dependence on a UK usage. Also was fooled by the spelling of 24: initially wrote in the "obvious" but wrong one and had to correct it to get 28. 17 was obvious from wordplay but I had to google to verify.
Can't recall FOI. 1 was LOI but 18 last to parse.
Too tired to select COD, but liked 1, 28, 4 and 10 among others.