I really enjoyed this - my fastest ever completion of a Paul, albeit some parsings came after the fact. Whilst I adore the taste of wine, I notice that abstinence definitely increases my mental acuity.
For 16a I parsed the overall answer as a synonym for the first word only. The first part of the word I thought a synonym for the second word in the clue as in “I’ll be heading off then” and then finish with the study group… if all of that makes sense without being too spoilerific at this hour.