Do what you enjoy and do it well. Studying something you enjoy will more likely lead to better results. The grades you get will be more influential to get into a Russell group university. However, picking those A levels will obviously lock you out of courses such as the likes of STEM degrees. Do you roughly know what degree study areas interest you? Also, if you can, start thinking about work experience/internships / from day one! Your future self will thank you, trust me.
I took Geography, Politics, English Lit and Biology at AS. I got an E in Biology and dropped it (picked it to keep my options open). Focusing on the other subjects at A level was much better for me and I did extremely well. Go with your gut.