I think the comedian is Deborah Frances White, she use to do lots of improvised comedy and am aware of her not being nice.
Can also confirm she does stand up - she did a charity gig & died on her arse/started trying to start an auction for tickets for her own show (which didn’t go well) and then started trying to bully the audience into making donations to the charity.
I’m another former Guilty Feminist listener, but stopped when Sofie Hagen left, although I’d already been put off by some really strange comments they’d made against breastfeeding (comparisons to parasites & “wanting to get your body back” - am fine with women having their own goals with feeding, but the emphasis seemed to be on looking good and not having any responsibility).