Hi Mat, I am too a newbie on here thought i'd start off replying to you! We've been trading for nearly 2 years now and started off using brokers such as carfinance247 - as I understand it you need to be FCA registered to use brokers too. We are now direct with a number of finance houses including Close Bros who have been great. They have a very easy system with quick decisions and fast payments. It is still worth signing up to some brokers as you can use them for those customers who don't get approved by Close - the commissions are much less but could save the deal.
We also use Worldpay and pass the credit card charge to the customer.