Object is to provide State support for a minimum level of income for any individual - £x per adult and £y per child on an age-related scale + £z special requirements (medical, disability etc. on another scale where appropriate)
Support = total - income from all sources.
End all national support schemes like free fares, prescriptions, fuel etc (local councils can still provide optionally what electors there approve / agree to fund but no general tax liability).
May sound like extreme means testing but that is only fair way and technology makes that easier than before. This can also work as unemployment benefit with proviso that anyone capable of work must take reasonable offer of work for benefit to continue. People will argue about 'reasonable' but agreement somewhere along the range is feasible.
Those with assets but no income would receive same benefit but if below pensionable age the total paid would represent a charge on their assets on sale or death. This avoids someone living in a valuable house or owning expensive items having to sell at an inopportune time and negates criticism of support for the 'wealthy' at the same time. State Pensions could probably be included in the benefit too but allowance will have to be made as people think they have 'saved NI conts' for these so some phased system required there or the opposition will have a field day.
Current complex system has evolved by tinkering over 60+ years and has become hugely expensive to administer with professionals thriving even on interpretative services. Total and complete fresh start required. Brave. Difficult to envisage but will produce a cheaper, fairer end product where other parties can only really argue about the numbers x, y, z etc rather than the basic concept and objectives which are pretty much unarguable.