query on casual work whilst on benefits

hiya!

a quick question... i am UC and LCWRA, my brother who runs a business has offered me to work a few hours for him (paid work) as a one off. i was wondering if this may affect my benefits at all, if i were to take him up on this offer? or if i would need to declare it to dwp etc?

I also wanted to double check something, i understand that if one is living at home, in family household (my Dad's house) it isnt possible to claim any housing element to pay him rent is it?

thank you so much again,

Best
Sarah