There are various online tools which can be used to check accessibility during the creation of a website. For example:
These tools can identify actual mistakes and they may also warn of areas where difficulties might arise. Whether these are relevant or not can only be found out through user testing.
It is good practice to consult with a variety of users, especially those who rely on assistive technology, throughout the design process. This will help to identify and sort out any access issues at this early stage.