VX N281VA Roona -- thanks so much, both, for the swift replies and excellent input! I genuinely appreciate it.

I was a little lost, admittedly, on how actually to book the inbound flight, and also a little unsure re the +355 and +330 discrepancy outlined above, but what you've both kindly written above is really helpful to that end, so thank you again.

As Roona says, too, my hope may be a forlorn one when it comes to actually finding F space at all on this route, but you've got to live in hope sometimes. Apart from the other CDG-HND-CDG route, I'm not sure that there are many other ANA routes to search for F space on in and around western Europe. (Whereas the various US airports that fly to/from HND with ANA seem to represent a good back-up plan if you can't find space on your preferred route, which is great, although I do appreciate that positioning flights have to be factored in.)

All the best