Would definitely go down the Wordpress/Premium motor trade template route.
I know a bit so managed to set up myself but you could use one of the freelancer hire sites (people per hour, Freelancer.com, Elance.com) to do this for you.
You could then get hosting for about £2.99 a month through https://www.vidahost.com/web-hosting
Let me know if you need anymore help.
Got mine through traders-insurance.com. Was with Tradex but got too expensive
http://www.traders-insurance.com/part-time-traders-insurance/
Wanted an online quote but struggled to fine a decent one so went through these guys (motor trader brokers rang me back).
Hope this helps!