Your POP3 account for collecting email will still remain account as you'll become a PAYG customer (I still collect mine and it's still live). You will need to change your outgoing SMTP server for sen ...
I'd ask for the MAC code around early Nov, not 23rd.
Give it to Be - say you''re migrated on the 10th Nov
Give Orange the 30 day cancellation notice the day you're migrated - this will easily take ...