I have searched but can't find an answer on the forum, however, apologies if my searching wasn't rigorous enough.

I'm currently Gold. If I make an Avios booking now and then, when I achieve GGL in January, want to change the booking, will I be able to change/cancel this booking for free (GGL perk) or will the T&Cs at time of booking when Gold (£35pp) apply. I know that (4x £35 = £140) is fairly insignificant compared to the cost of achieving GGL, but I'm just curious.

MTIA
Ian