and third, good luck finding a dealer who'd let you buy a car using a credit card"But if I was to purchase a car around 13K and got a credit card with 0% and pay it all off within 12 months or so"
Am i reading that right, that you want to get a 0% CC and buy a car on it for £13k ??
Firstly it's unlikely you'd be offered a CC with that much available credit as like you said you've no history of paying off loans,
and secondly using more than ~25% of your available credit can negatively effect your credit score