I've been working alongside claiming UC for several years. I started at a school two years ago.
Whenever I go to the dentist I fill in the form correctly and tick the UC part.
I've just seen online that if you earn over a certain amount working then you do pay for some after all and I had no idea 
Apparently people are getting fined, I'm shocked, I've never lied or knowingly deceived anyone, I'm not sure what's gone on or what to do.