ATC hopeful im in the same boat as you. Jusy passed new stage 2 and have booked my stage 3 (8th april).
I have been trying to get in contact with HR since yesterday regarding a NATS visit and to clear up if we will be asked any questions on motivation papers (im assuming not as i didnt get a link to a document either).
I've not had much luck getting through to them. Today i spoke to two seperate people and both just took my contact details to get back to me. Although one person at HR said that regarding the NATS visits that someone from the recrutiment team would help me organise that and she asked if i had a preference for where i wanted to visit. But other than that i've not had much luck.
As far as my hunch on what stage 3 interview may consist of, i thought it would be a mix of HR and technical....but as we have no formal motivation paper to revise and there was no mention to revise past motivation paper info, i have a feeling it will be just HR based and then maybe just basic company information as it does refer us to the website.
Let me know if you hear back from HR regarding the interview anyway.