Any advice on impressive projects I can make for Oxford/ Birmingham Compsci/maths?

I aim to do a joint computer science and maths degree. I understand for the maths portion, I should read around the subject, delve into more niche topics and practice for the tmua, but on the area of computer science, I'm not sure what i should really try to do that can go 'beyond' and actually help people in my community through code. Any ideas?

I mean you don't have to do social impact projects if you're struggling for ideas. Why don't you do what you've done for maths with CS?
Find a niche topic that interests you and delve into it.

I feel like i find finding niche topics for cs harder than for maths, and I feel I'd enjoy something more practical, but I have been looking at some things specifically concerning maths and comp sci

Practical in the hardware sense or just building a project?

hardware, yes. i am interested in robotics!