Impressive courage and good luck!
It is fine to have a programme without any sonata at all. Any one of your options deems to be balanced, but when you apply for approval of own choice(s), you can only send one. So, I would suggest you to whichever one you are most comfortable. Nonetheless, please allow me to share my thoughts.
Toccata from Bach Partita No 6 is actually fairly difficult, as I am using the entire partita for my upcoming FTCL challenge. However, I suspect the assessment of this piece at ATCL level will be less demanding. If you aim for FTCL in due course, then perhaps you pick another baroque piece so that this toccata can be used later. BTW, Scarlatti K27 is seemingly a popular choice for ATCL as many students used it for their ABRSM Grade 8.
I think that your Mozart K475 will likely be accepted as own choice. It is on Licentitate syllabus of Royal Conservatory of Music. Yet, often I hear that whilst a Mozart piece as the choice for classical period seems to be relatively safer(?!) and easier(?!), it is actually quite hard to score high because the candidate needs to make it sound Mozart. However, as you did mention, you know and love the piece, I suppose you have nothing to worry.
Last but not the least, there is no requirement on the playing sequence, i.e. not necessarily starting from baroque. Some teachers suggest to start with one of which the candidate has most confidence, and end with one that has brilliant/sonic ending sound.