for me, for the first year all the new phd students are being registered as MPhil student before differentiation. so am planning to make the most of it and work for 20 hrs a week. after differentiation its 6 hours and for a business phd you can take two days off and work coz you have no obligation to be in a lab or in the lib. after differentiation try getting a teaching job, you'll earn the same as 20 hours a week doing bar work or even more for the six hours a week teaching.