If you are looking for the rockingest acoustic session in Essex, it's on at the Coast Inn, in West Mersea, 8 miles south of Colchester, every Thursday night.
The acoustic of the venue is excellent, wooden floor, no soft furnishings and varied ceiling heights. The beer is excellent, currently Green King IPA, Mersea Island Brewery's Yo Boy! and Captain Bob from Maldon.
But be warned, musician seats fill up fast, as do the remainder for listeners/drinkers, so it's wise to arrive about 8pm. And don't expect an early night - the music usually finishes about 11.30.
Music style is widely varied, from Irish, Scottish, English and American tunes to bluegrass, jazz and rock, with songs from many genres. It is a completely inclusive session, with no cliques or rules, just respect for fellow singers and musicians.