I assume you mean Private Limited Company as opposed to 'Pvt'?
If so, then you pay tax on your profits. Wages (ie. Your salary including income tax etc) are classed as an operating expense and thus you do not end up paying the equivalent of 42% (22% corp 20% inc) tax, if that's what you're asking.
For more advice I would seek an accountant, as there are different ways to get money out of a limited company if you are on your own (dividends for example).
Most basic example I can think of is that you earn £100 for the tax year.
£80 of that is your salary. YOU pay £16 in income tax (80 * 0.2).
The company profits £20 (assuming there are no expenses) meaning it would pay £4.40 tax.
That's a very basic example and of course there are other things involved.