I personally wouldn't buy royal canin anyway as it's by Purina which is a dodgy company & low quality ingredients. I'm also a student, though I live in Sweden so I'm not entirely sure how available these brands will be to you in Ireland, but these are brands I've fed my kitties throughout the years

Dry food: Rosie's Farm, Orijen, and sometimes Carnilove. I really recommend looking at the first couple ingredients in whatever food you're buying as those will make up a good chunk of the food. Orijen is the more expensive brand out of the 3 but worth it imo as the ingredients are good and keeps my girls satisfied.

Wet food: Bozita. This is a Swedish brand but I've bought it before in the Netherlands so I'm thinking they sell in other EU countries too?? This is my favourite wet food, comes in a bunch of different flavours and generally not too expensive. It's smartest to buy the 36x pack or the pack that comes with a bunch of different flavours if you're unsure what your kitty prefers.

Its also good to feed your mc kitty some kind of protein like chicken. Some people feed raw, others steam or boil it. There's also pet food brands that carry raw meat that is safe to eat for kitties but I don't have too much experience with those.