I just bought myself a new pair of trainers. The shop assistant was really knowledgeable and helpful. Apparently I have low arches and naturally stand on the outer part of my feet.
Was totally worth getting my feet properly assessed and matched with a good pair of running shoes rather than me just trying pairs on not knowing what would make a difference. Also, he gave me a tip about how to make them last years and years: get new inners every 6 months or so.
Now to see how they feel whilst running outdoors!