The UK doesn't do great sitcoms. For example The Thick Of It has to be one of the funniest shows ever, yet couldn't be described as a sitcom. From recent memory the only ones that have really made me laugh were Friday Night Dinner, Him & Her, Pulling and the sadly departed IT Crowd.
Funny female comedians seem quite thin on the ground other than those already mentioned, especially in the UK. Sara Pascoe is good, some of Laura Solon's stuff on R4 is excellent. Shappi Khorsandi gets a lot of good press but whenever I've seen her has been largely poor.
Bridgett Christie seems decent, Josie Long is funny at times although I saw her late at a festival and she sent me to sleep.
Not strictly a comedian, but I'm going to mention Sharon Horgan because I want to marry her.