Sorry i cannot offer a helpful tip or two but wanted to say dont give up. My friends daughter was in the same position as you - qualified but lacking experience and desperate to be a legal secretary. She managed to get a temp job but hated it. She continued to search actively and was rejected time and time again. Someone mentioned in the lunchbreak a position for a junior going in London and so she applied and got an interview. She wasnt going to go the day before as she felt it would be another rejection.
Not only did she find a job, she so impressed the company offered her a higher position. She now earns good money and the company has subsidised canteen, free hairdressers in the building, cheap holiday offers, a gym and freebies from famous Cola company who are one of their clients. She had been trying for almost 18 months before this break so keep trying - someone will see your potential. Good luck