The rest of us would then have to pay marginally more tax, wouldn't we, if doctors pay less?
Are you being serious? 
It's taxes that pay doctors' salaries. If they are paid less, less tax money is needed.
Any tax that doctors pay is being recycled back into the pot it came from.
If someone is paid £100k, there's approximately 35k in deductions.
If someone is paid £50k, there's approximately 15k in deductions.
In the first case a net £65k leaves the Treasury, in the second a net £35k leaves the Treasury.
In what world can someone being paid more out of public funds equal the rest of us having to pay less taxes?
By that logic, paying public sector employees an infinitely large salary would result in no one having to pay any taxes whatsoever! 