Here’s a quirky thing I somehow just learned about Avios bookings:
I made a booking for a friend using Avios miles and I wanted to change one of the flights. Changing the flight would cost $40. If I canceled the itinerary and just booked it again, they would only charge $5 for the cancellation fee. Both flights still had availability, I cancelled and re-booked, which saved me $35. I have no idea why they do that, but I just thought I’d pass along.