my op cost £3600 because i had a £250 off voucher, i paid 3500 off with the credit card and then a few days later when i was paid rang up and paid the last 100 off with my debit card
kayteelouu ill explain mine it might help abit. i got £3500 credit card which works out at around £300 a month. basically with my barclays platinum card i do it online. you have to pay the minimum payment each month by a certain date, mine is about £80 a month. but if i want i can choose to pay off as much as i want. takes a minute to pay, i was so worried about getting a card but aslong as you pay off your minimum a month you wont get charged for anything.
if after a year you still have money on it you can do a balance transfer onto another credit card from another company for a small fee, usually 2% of what you have left on your card, then you can get another years free interest with some one else.
you can choose to set up a direct debit with the same amount each month which is good if you have a set wage and know how much you can pay a month, or when your paid from work you can just pay online using your debit card, ring up or send a cheque to them. onlines great - its got a bar that goes up or down everytime u pay something off or use it, really simple 
i just pay it when its due and do what ever i can afford, i aim for £300 a month but this month was less as ive had less hours at wrk.
sorry for waffling haha but hope it may help a little
