Thanks! We would cancel well in advance of the flight (like 10 months). This would be a tentative (hopeful) booking that we may not be able to complete, but if that is the case I would know within a month or so after booking.

When I canceled a BA flight once before ( to re-books different date) the Avios and the money both appeared in my respective accounts within the hour. I won't need them that quickly this time, but just want to be sure I get everything back.