EDDIE 51 is largely correct.
However, restraining orders are reasonably uncommon. There will need to be a sustained log of harassment involving both parties which has been routinely reported to the police for the judge to advise this. If this is has been a spontaneous incident, there will be no restraining order.
It will likely be the same judge, but as Eddie said, it could potentially be whoever is in court on that particular day. In either eventuality, the judge will be provided with a presentence report giving an assessment of the guilty party's character. This will affect your partner's ex-girlfriend's sentence.
I suspect, judging by your assessment of injuries as minor, that she will receive a medium-term community order and possibly a fine.