Pandora, have you tried AAMI online and used their quote calculator?
They tell you how much it will be, but also email the quote to you (if you tick that box) with a clickable link in it to go back and retireve it and pay. I'm sure once you go through the whole quote, it gives you the payment options, I do remember monthly being on there. You can do the whole process without having to pay. I did a quote for our new car when we were just looking at it online. Was about another 3 weeks before DH had all the paperwork organised, and a few days before he picked up the car, we clicked on the link in the email, went back to the quote and paid for it online (with CC though, so did not take any notice of bank transfer or monthly withdrawals from bank accounts)