Besides the Colchester club itself, it's definitely worth visiting

Wivenhoe Folk Club

And also Millbay Folk Club at "The Royal Marine" Walton-on-the Naze, which runs on the third Friday of the month - you should be able to get details from Thrift Music as Jon & Pam organise the club. The pub is one of the central venues for Walton Folk Festival in September, and also hosts a Shanty/Seasong weekend in November.