These threads don't half evolve....
There was a programme years ago where an MP tried to live on UB and wasn't able to. It would be really hard especially once any number of consumer electricals broke.
£400 for food and utilities. Sounds doable short term. But no TV, internet, phone, car, clothes, etc etc. It should be that working full time should significantly increase comfort levels. That people don't must have a huge variety of reasons beyond just laziness.