Just received a response from TFL about the topographical test assessment from TFL:
TfL are in the process of approving assessment centres to host topographical assessments. Once approved, TfL assessors will deliver the assessment at the centres. Details of the centres will be published on our web page. For the latest update, please visit tfl.gov.uk/topographical
In the meantime, topographical assessments are available at a TfL office. Applicants can book an assessment by contacting us on 0343 222 4444. Please note, to book an assessment, TfL must be in receipt of the Drivers application to be a Licensed Private Hire Driver.