You may have been recommended funding toward some general costs such as printing costs. In these cases you keep receipts for whatever item you can claim back and send these to your funding body. They will then arrange for the cost to be reimbursed, up to a maximum amount per academic year. This amount will be specified in your needs assessment report and funding confirmation letter.
If you are funded by Student Finance England, you will need to complete a claim form. These can be downloaded from https://www.gov.uk/student-finance-forms – click Start Now and after confirming your student type then click the option to claim Disabled Students’ Allowances expenses.