If you are from a low-risk country you should still collect all the evidence listed above. ISAS will still need to check and approve all your documents before issuing you with a CAS.
The low risk countries are listed on the UKVI webpage.
If you are self-submitting a postal Tier 4 (General) Student visa application and are from a low-risk country, you have the option as to whether or not you wish to submit academic qualifications or financial evidence with your application. The UK Visas and Immigration (UKVI) can ask for these documents when it is processing your visa application.
If you are asked for this evidence while your application is being processed, you will be given a deadline by which to provide it. If you fail to provide the documents when they are asked for, your visa application will be refused.
If you will attend an appointment with the UKVI, you must provide all the documents.