teeteringhead, I don't think you actually read the question and you certainly didn't read all the other replies.
Ultimately you do not of course really get to keep anything it is all converted into goods. At every turn there is a tax take. Even VAT free items, like newspapers, have a tax slice of corporation tax, employer's NI contributions, employees' tax, and even VAT and NI on what the employee earns and spends.
I guess the short answer is that ALL your money, less the cost of material bought in from outside the UK, like Kenyan Beans or your overseas holiday, finishes up in the treasury.
The money for the Kenyan beans finishes up in their treasury, a swiss bank account, or back in UK for goods they buy.