If you've got the Abbey Zero card available to you giving 0% for 6 months without a BT fee then I would move your £2500 to this for 6 months then seek to get a 12 month 0% card with a BT fee of 3% or lower.

If you're spending £500 per month on expenses which you claim back then I suggest you also apply for the Egg Money Credit Card which pays you 1% Moneyback annually on all spend made on the card. Pay this off in full every month and this will make you an extra £60 per year based on £500 per month.

Cheers

Joe Burns