As per the below paragraph in the OP
Once I pre-ordered, Apple placed a hold on the funds in my account but released it a few days later without taking the money. Is there something wrong with my order?
When you pre-order from Apple and pay by credit or debit card, Apple will at some point place a ‘hold’ on the amount with your card company. This checks you've got the funds, and stops you spending them. However, a hold only lasts a few days, after which time your card company will automatically make the funds available to you to spend again. When you see this happen, it is nothing to worry about, it DOES NOT mean Apple has cancelled your order. Apple will not take the money out of your account until the day of shipping.
I've noticed that Apple have actually taken £999 from my account. Will this therefore be refunded in the next couple of days? I ordered for in-store pick up and will be setting up IPP.