Where the money comes in
Income tax, National Insurance and VAT raise most UK government revenue. Each is collected differently, and each falls on people in different ways.
Where it goes out
Health, state pensions and other welfare, and education take the largest shares. Debt interest is a real and growing slice that buys no services at all.
Why the arguments happen
The budget is finite, so more for one heading means less for another or more borrowing. Political disagreement is usually about that trade-off, not about the arithmetic.