I just took out a policy for a van that will last me a month or so, after googling/search engines I found out (in my case anyway) it was easier to just buy an annual policy and cancel after the two months i need it for.
I made sure I could cancel without paying for much more than 2 months worth though, as some will let you canel after a month even, but only refund you around 60% or worse.
Jordan