Looking for some advice about how I can find my studies.

Am trying to obtain an EPSRC studentship but am finding that the stipend rate just won’t be enough to live on after doing some financial planning. Is there any way that I can top this up while still keeping the full-time studentship? e.g. with a part time job or a research assistant job? What would be the maximum hours I could work alongside a full-time studentship? If I can’t work, how about income from teaching and demonstration?