Do I have to use the official application form?
No, you don’t. It is, however, probably in your best interests to do so. Before an application can be accepted by a public authority, it must meet the minimum requirements as set out in the regulations, and the application fee must be paid or a waiver granted. Forms created by public authorities have been specifically designed to ensure that the minimum requirements are met if they are filled out correctly. So a good way to confirm that you are making a valid application is to use an official application form.
If your application does not meet all of the minimum requirements, there may be unnecessary delays in processing it.