I'm a single parent of 3, and we're still receiving tax credits (haven't been migrated over to UC yet). I don't know exactly what they've done with increases/thresholds but the actual amount I receive hasn't increased in line with inflation for years. Some years its gone down, despite my circumstances (earnings) barely changing. I'm convinced most benefits haven't genuinely tracked the rate of inflation in real terms for ages.
And according to online benefits calculators, UC in my circumstances is actually less than the current child tax credits calculation (I appreciate transitional protection should cover the difference, but as I'm self employed I'm not sure that'll actually last long).
I don't qualify for or receive housing benefit, but I know people who do. And there is no way that has increased with the real rate of rents for years either. Currently there is no way that it will cover actual private rent charges. Someone entitled to single bedroom housing benefit gets £440 a month. That's supposed to be the rate for self contained living accommodation, not a room in shared accommodation. There is nothing self contained available to rent for less than £600, typically it's more like 700+ (and that's if you can actually find somewhere).
The national min wage has gone up significantly over the last few years, but benefits amounts and thresholds haven't been adjusted in line with that.
Yes there is a problem with the social economy in this country - it shouldn't be necessary to prop up by household incomes with government handouts yet still leave people below the poverty line. I don't know what the answer is, but things are badly broken in this country.