Re sitting the year?

I got an A in sociology, a D in biology and a C in geography, and I was wondering whether or not I should re do the year?

I didn't revise much for my AS'. I revised sociology for about a week and then did geography in 4 days and biology for about 3 days, so I feel like if I committed more I could have gotten much better results.

I want to do accounting and finance at uni - a decision I made earlier this year otherwise I would have chosen more appropriate subjects at A level - but I was thinking I could just re do the year with more relatable subjects, and subjects with higher grades.

But my teachers also said that there's no real need to re do the year if I just revise hard for next year, plus you can do accounting at uni without having actually studying maths or accounting. However I was hoping to apply to some Russell group universities and I don't think they'd give me an offer on these particular grades even if my personal statement was good.

If you have any advice on what I should do it would be much appreciated. Thanks.