Maybe it's just the mood I'm in but I really enjoyed this. It's peppered with lots of humour and wit.
20a I'm shocked! I can't ever recall seeing the first 4 letters in a crossword before.
I don't know if this was intentional or not, but 4d could be rhyming slang for 8d and vice versa.
22a Our cousins across the pond will find this easy but it may prove tricky for some of us Brits - revenge for yesterday's Guardian Prize (6,3) perhaps!
1a brought to mind the "all change for Leeds" skit in either Not the Nine O' Clock News or Monty Python.
COD 8d - very witty and well constructed.
All in all a very enjoyable puzzle. Thanks setter.