Nike Air Force One, leather Camper style as shared by someone further up, Adidas Advantage, even Adidas Gazelle (though maybe not for an interview, def ok for work though in my industry)... High street versions of these trainers - the kinds of things that hang up in Next or you buy at Cos - also fine.The key is clean, with clean laces. If they're trainers you'd wear to the gym, or walking the dog, they're not smart trainers.
I don't work in London, or in any major city, and while I am 'a creative', the client facing peeps don't dress formally. Smartly, yes - not formally.
If the OP doesn't feel comfortable in trainers, all good. The most important thing is wearing something that feels 'her'. But if I were her and didn't fancy smart trainers, I'd wear an ankle boot I already had with the trousers and top she describes. The loafers she shared are really quite formal, and design environments are always smart, but rarely formal. Pointy toed flats would also work if she has any, or mary janes...