I agree with both Barleyfields and Cossy. Minimum wage should mean that nobody works a full week and needs top-ups. At the same time, I see no reason why people should be able to work half a week for a whole week's pay. Again, that comes down to unfairness on those who do work full-time on the same hourly rate and do twice the work for the same take-home pay. It also means that taxpayers are propping up the profits of low-paying employers.
Childcare needs to be looked at, too, as in some cases that would eat any extra pay for extra hours worked. I would like to see state nurseries providing free or very affordable childcare to all working parents who want it.
Of course people should be able to work P/T if they want to, but there shouldn't be so many jobs with deliberately short hours that mean employers are not obliged to pay NI, and employees are not entitled to sick pay, maternity leave and pensions, and those who choose to work P/T should expect to get paid pro rata.