Even taking away all the wasteful spending there's just not enough income to pay for all that is needed. Roads, rail, schools, hospitals, elderly care, and all the rest. I don't understand why governments of all flavours are so afraid of simple taxation. Income tax simple, the more you earn the more you pay wether that's 10% 20% or 30% VAT simple, the more you spend the more you pay, wether you're buying a fiesta or a Rolls Royce. Get rid of all the sneaky taxes, loopholes and exemptions. It probably still wouldn't be enough but it could be simpler to understand.
The tax being collected is being spent on basically everything. Unfortunately there are people that try and avoid paying tax, and people wring as much as they can out of the system, such as the consultancy firms charging enormous rates to advise the government. There are too many middlemen taking a cut