Buy European

I went for Harringtons in the end as they seem to have a good balance between value:nutrition, are european and similarly priced going direct which helps.

I mention mostly to be told I've made the wrong decision for future learning lol

Have you looked at zooplus.co.uk or their "outlet sibling", bitiba.co.uk? German company selling many German cat foods, such as Animonda Carny (my regular), MAC's Cat (my cats' favourite), or anything made by Matina Gmbh, such as the similar but cheaper wet food brand Smilla (varied acceptance by my cats, also has dry foods). All these wet foods have a rather "chunky spam" consistency, adding a bit of water and mushing it in may make it tastier (and add water yay!), but it also means it's very nutrient dense. You only need about 200g/day/cat, whereas you need about 300g/day of eg. Whiskas, essentially paying for water. Bozita is Swedish... Probably others that I forget.

Ultimately it'll depend on your cat. Get her to try various different things, and see what she likes. I am gradually replacing whiskas with Sainsbury's own and it seems to work. For reference I also tried giving her Asda's own but all the biscuits I slipped in got untouched.

Aldi have what I presume is their own Vitacat range. They're likely a pretty good copy of other more expensive cat food brands at a lower price and Aldi is a German company. I don't know the specific country of origin but for standard things like that it is usually made in the UK or EU (a quick check shows they don't list it these days, but used to - dairy products used to come from Ireland, for example).