Leraud: Wheatsheat session stopped some time back now. It's split into two now, a "serious" session at the Red Lion and a "non-serious" session at the Bees in the Wall, both on every Friday night. The Red Lion session is more of a "proper" session - the Bees is more just a bunch of musicians hanging out in a pub for fun.

Some others:-

Acoustic Routes club at CB2 in town
Cambridge Folk Club at the Unicorn (Trumpington Unicorn, not Cherry Hinton Unicorn!)
Mayflower Folk Club at the Portland Arms

Graham.