Will I still be able to become a nurse after my visit to occupational health?

Just be honest at occupational health, they don't want to stop you they just need to check that your well enough, which as your issues of self harm and depression were more than a year ago it's very unlikely to be a problem. I was in the same position except having borderline personality disorder on top of depression and self harm but they were satisfied that i was managing well enough to do my nursing training and they just kept an eye on me with regular appointments. As for the scars showing when wearing your uniform, i found that no one else had an issue with this and no one ever really mentioned it, i was the one that was uncomfortable with them on show, but i got used it and as long as you don't mind then do what makes you happy.