Q: I am finished the theory of my Level 6 course, but I need 18 months work experience to get my Diploma.
A: Most colleges have a Work Integrated Learning (WIL) department and it is important to get in touch with them as soon as possible. They may not be called WIL at your college, but inquire there.
If you are not successful consider working as a volunteer. You may not get paid, but you will gather experience. Ask at the WIL office.
BUT you are also expected to look for your own opportunities. Here are some articles which may be useful:
There are more articles about CVs, Cover Letters, Interviews and so on, in the WORK section here
Scroll down when you get there until you find WORK.