I'm in Essex , I ride through Higginum several days a week.
If you're interested I co-lead Thursday evening rides in Essex with AMC. These are Sho-N-Go, no route notes. We wait and don't drop anyone. More of a social ride. Pizza after the ride
Other local rides I know of
Monday 6pm Pedal Power Middletown- Several groups A, B, C etc
Tuesday 6PM Manchester AMC Several groups A, B, C etc
Action Sports Old Saybrook, Thursday evenings- Faster training ride 18Mph-20 + average from what I'm told
Clarkes Cycles Essex,Tuesday and Wednesday 6pm rides . Both are 16-20 mph