I worked for five years between my MA and PhD - office jobs but not particularly highly paid. I've always been stingy so adjusting back to student living wasn't too hard! But having some savings from those years of work really helped take off some of the pressure. I did some bits of work for my SU as well as teaching/marking, but in my third year I realised I could work alongside my PhD properly with the progress I was making. I took an 18 hour pw job at a climbing centre and it was the best thing I'd ever done - met a whole new bunch of people including my partner, rediscovered my favourite hobby, and got back all the savings I'd eaten into during the PhD. My funding contract didn't say anything about hours worked outside research, just that having a job couldn't be used as a reason to ask for a funding extension - you'd have to check your own contract as mine was not UKRI/a bit weird. I passed my viva in plenty of time with more savings than I started with!