If you want to go into concept design, then maybe ICT would be good? Then you'd learn basics of software, which is always helpful. As a graduate who didn't do a STEM degree, I can see now why schools always pushed people towards STEM. Even if you don't want a STEM degree, the use of technology is a big advantage in basically any job, because it shows you're can think analytically and good at problem solving.
Ultimately though it is up to you, and unless you want to do a job that specialised, uni's/jobs don't care about what you studied as much as they just care about the grades. So if you enjoy a subject n score well in it, go for it. I studied international business at uni, but 2 of my levels were history and RE for example.