Sadly no ACH 400 all myth. True dat no pubs on a Sunday morning in Greenwich but you should be able to kind of time; I assume you don't want to sleep on this? Down to Downs was always good training for me.
B roads longish climbs and descends and Langton Green and Pratts Bottom service station 24h for the night. Do it four times and the Shark and you qualify for the Grimpeur du Sud medal as well.