Yes you can get really obscene amounts of benefits, example:
Couple with 3 children in London, 1 parent works 24 hours a week at NMW (£8112 per year), the other doesn't.
Tax credit entitlement: £12,171.18
Council tax benefit: £855.17
Housing Benefit: £17,422.95
Child benefit: £2,501.20
Total benefits entitlement: £32,950.50
Gross salary: £8,112
Income tax: £0
National Insurance: £6
Free school meals (3 children): £1311
Net income: £42,373.50
And before you ask, NO the benefits cap doesn't come into play, because you are eligible if you claim Working Tax credit.
For comparison, second couple, 1 parent works 40 hours a week earning £60,000 a year (cue HOWLS of protest from Mumsnetters when they complain about the cost of living - you are rich, etc. etc.), also 3 children
Total benefits entitlement: ZERO
Gross salary: £60,000
Income tax: £13,403
NI: £4,471
Net income: £42,126
So the £60k family has a lower net income than the £8k family. And is even worse off in reality when you consider things like discounts for WTC recipients, free prescriptions, free dental, free glasses, discounts for leisure activities, and so on.