Apply to become a London taxi driver?
The Transport for London website is notoriously bad when it comes to applying. Here is the direct link to the application page.
Application Page
However, it is recommended that you read through the accompanying pages. Some of the information is nonsense, such as the phrase “Before you can start learning the Knowledge, you need to apply to be a licensed taxi driver and have your application approved.”
While it is good to apply early to avoid complications arising closer to you getting to examination standard, it is not a requirement for you to have applied before starting to run the Blue Book Runs.
The information you find here will probably not be news to you if you have spent time reading through everything presented on this website, but feel free to familiarise yourself with the TfL website.