Hi: Go this web site: Cambridge-news.co.uk
I tried it and it brought me to this page where if you scroll down the page under Listings, you will find a heading called,
Folk/Country and it lists all the current folk venues around Cambridge.

Also, I have found that you can call the club and find out what bus to take that will bring you close to their location, (if you don't have a car). Most venue managers usually know this information. Or else contact the transit agency and give them the address of the venue for bus information. Some clubs are not always by the central part of town, and may be just on the outskirts but hopefully you will be able to find some to go to.