don’t pay on CC unless you’re prepared to pay more – dealers don’t like it as it costs them.
I would advise the opposite – DO pay with credit card – but just the deposit so the dealer doesn’t lose out on fee’s, etc. As long as the deposit is over £100 it covers you for the whole transaction – the credit card company are then liable for any faults with the purchase, as per your rights under S75 of the Consumer Credit Act.
http://www.which.co.uk/consumer-rights/regulation/section-75-of-the-consumer-credit-act
If you have a credit card you would be mad not to do this, it doesn’t cost you anything (and very little to the dealer) and another way of resolving any disputes that may arise down the line.