Flexible PhD process
It may be possible to start a PhD process while studying for your Masters, for example by signing up for one of the flexible PhD systems (also called the 4+4 or 3+5 schemes). In the 4+4 system, you start 12 months after the beginning of your Masters' studies. In the 3+5 system, you start on an integrated Masters and PhD process straight after graduating with your Bachelors.
If you start your PhD studies as part of a Masters programme, you will be admitted as a PhD student at the same time as starting your Masters studies, and you would normally be expected to complete your Masters at least two years before the expiry of the standard duration of the overall PhD study process.
If you are admitted on the 4+4 scheme, you would normally have to complete your Masters in two years. For students admitted on the 3+5 scheme, this would normally be after three years.
To learn more about the opportunity for a flexible process, please vist the the individual graduate schools' websites.