the 10% code will work for credit card as the code is entered before you choose the payment method, I've used the code and paid with mastercard.
btw I dont think the BD mind either as its not in the T&C's that we must use paypal:
but as tommythethumb said they charge in advance for pre-orders
but you have to check which website is cheapest when you include the 5% or 10% discount as sometimes the .co.uk and .com have different prices for the same item