Hi mhshah,
Indeed that is correct, to book the IPA you will have to attend the initial Ignition Session to engage in the Uber process. Unfortunately, Uber have temporarily suspended new applicants for the time being, so at this time you will not be offered the opportunity to attend an IPA until they commenced recruiting again. Regarding the IPA itself, it is extremely straightforward and an elementary exercise, if you have reasonable English writing and language skills you will have no difficulty, the session lasts 4 hours with a 28 question test at the end, there are no questions that are not covered on the course, so if you pay attention to the presentation and understand some of the terminology you will be fine.
Following the IPA you will attend the Uber office to process your licence application.
If I can be of any further help please do not hesitate to contact me, otherwise attend the Birmingham office whereupon you will find the Uber team extremely helpful and understanding.
Best of luck.