The Acoustic Calendar for Wessex (formerly Tony and Peter's Folk Diary)
The Acoustic Calendar for Wessex is the best guide to singarounds, acoustic sessions and open mic in the Wessex area there is.
The Diary is issued each month during the previous month, each one including an alphabetical list of the venues giving contacts and other details.
However, please beware of treating it as gospel. People have followed the diary only to be disappointed to find nothing happening. The reason is that schedules are subject to change and cancellation, and they're not always informed. So, if you intend to visit an unfamiliar venue, particularly if it involves a lot of mileage, please give the venue a ring beforehand to make sure you don't have a wasted journey.