You can find information about trusts and charities that offer educational funding from the Hotcourses Scholarship Search website.
You might find the following books useful:
The first step is to write to your chosen trust or charity giving a summary of your situation. If you fit its funding criteria, the organisation will then send you its own application form.
You should include the following details in your letter:
Make sure your letter is well presented. You might also need to get a reference from your course tutor or the Student Life Centre, so make sure they'll support your application.