I work in a Post Office and the other day I had a customer purchase some NS&I Premium Bonds and wanted to pay for it via his Credit Card. Now at the time I was certain the system wouldn't let you pay for anything like that by credit card - only cash, cheque or debit card. But he told me he used his credit card in the past. So we tried and it went through fine.
Now I'm 99.9% certain that that transaction will show up on your credit card statement as a PURCHASE (Post Office Limited). So I bet your wondering where I'm going with this don't you, well....
Buy £500 of premium bonds on your credit card, take advantage of interest free periods. Cash in your premium bonds as soon as you get them and you've got a cash advance without paying the fees or the interest.
A Lot of credit cards offer vouchers, points, air miles for example. Buy Premium Bonds, pay your credit card bill off in full, so no interest and cash in your bonds.... Great way to collect your awards from your CC company if you've cash flow can let you.