Wanting to book a flight in J with Avios leaving on a Wednesday, but was thinking about booking the ticket leaving Tuesday, just in case. And then if there is availability on Wednesday, I will cancel the first booking and rebook. I'd rather do it online than on the phone. So 2 questions, 1) can that cancellation or change be done online? and 2) will the Avios from the first booking be available right away or will I have to front a new set of Avios and wait 30 days for the original Avios to be refunded?