How can I boost my Oxford application for English?

I will be applying to study English with enrolment 2019. By the time of entry, I'll be 21 meaning I will be a mature student. I already have 3 A Levels at A*AB but I am taking two further a levels this year, hoping to achieve grade A's in both. I also have 4 A*, 9 A and a B at GCSE.

As I'm only taking two A Levels this year, I may have a bit of free time and so I am thinking of picking up some voluntary work. My question is: would the Oxford professors really care if I were to volunteer at the local newspaper for a short while, or something similar? Or perhaps my time would be better spent simply doing further self study?

Thanks!