Suits me MM, especially the gentle pace bit.
Now, SW is mid-ride for me. Do you know the McDonald's at the Harlow M11 Junction? If you could ride / drive their that'd be good although I don't think you could park for that long, so the alternative (if you want to drive) is to meet me at High Beech in Epping Forest where you can park all day (plus there's the tea hut for post ride tea and cake).
Are you happy to ride early-ish - approx 9am? Whats the priority - scenery or riding? The default route I'd use has a few main roads & 2 small towns - say 10 miles of that and 30+ Essex country - this has the best bank for buck with 3 x Cat 4's included? There is another flatter route into the wilds of Essex but thats closer to 80k and at gentle pace you'll have forced me into grovel-mode with the wife.
Your call (not sure how well you know the area).