@AuditBird
"Who is talking about five quid too much? From what the OP said she's working full time. That means she isn't entitled to benefits, housing benefits, council tax benefits, free prescriptions and free dental care."
Whilst I agree with everything else you've said. Working full time does not necessarily mean you can't claim benefits. If she was pregnant or had a child under 1 she could claim free prescriptions and dental care, regardless of her income although this would stop once baby is 1. CT benefit, probably not. Depending on a person's circumstances claiming Universal Credit whilst full time employed is perfectly possible. For example, if I go back to work full time on £27,000 per year in a year's time or whatever after maternity leave, I'm part time but anyway.
My entitlement would be as follows.
Personal allowance - £317.82
Housing element - £701.91 (2 bed entitlement for my area)
Child element - £231.67
Childcare element - £646
Total entitlement before deductions - £1897.40
Take home pay - £1812
Work allowance - £198
Total earnings taken into account - £1614
Earnings deducted at 63p/£1
Total deductions for earnings - £1016.82
Final UC award - £880.52
If you take the personal allowance first off of the total deduction of £1016.82 that leaves £699 to still be deducted. So less than my housing allowance award. I would still be getting £2.91 towards my housing costs (minute amount I know, just pointing out it's still technically there) plus child element and child care element. So yes perfectly possible to be earning a reasonable salary full time and receive benefits.