Originally Posted by Raffles
If it was treated as a cash advance then you are sunk - 1.5% fee from your credit card issuer, 1.5% fee from the PO, £10 card fee and £2 per withdrawal. Its not going to be attractive at that rate, unless you really need to boost your Amex spending to get to the £10k.
I'm 99% sure it would treated as cash, it is after all a cash instrument like a travellers cheque. Also, there are better pre-paid credit cards out there, you just need to search for them.