'Tis true, Audax is not well publicized.
However you don't have to join (just pay an extra £2 for insurance for each event if you don't)
200km is just the first of the randonneur distances, there's 300km , 400km, 600 km 1200 km

. But seriously, some of the most popular events are 100km
Till Receipts are not always required. Didn't need a single one on today's ride.
For my £8, I got...
Cup of tea, choccy biccy and banana at start
then at 30 km, ham sandwich, boiled egg, cherry tomatoes, more tea, another choccy biscuit
at 70 km, two helping of beans on toast, three cups of tea, tinned apricots & rice pudding.... had to leave before they pressed any more food on me and rendered me immobile.
at 107 km, more apricots, a slice of rasberry roulade, a slice of a nutty roulade, could have helped myself from the cheese board if there was any room, a banana or three, and more choccy biscuits (as many as I could carry) for the ride home.