It is not mandatory to have a student bank account before applying for student finance, but it is a good idea to open one if you're planning on receiving student loans. Most student bank accounts come with added benefits such as interest-free overdrafts, discounts on various goods and services, and other incentives that can help you save money as a student.
When you apply for student finance, you'll be asked to provide your bank details so that your loan can be paid into your account. If you don't have a bank account at the time of application, you can still provide your details later when you open an account.
Having a student bank account can be beneficial when receiving student finance, but it is not a requirement.
Hope that helps.