Even though you are a small office, is it a branch of a larger company? Is there a corporate HR person you can talk to?
If it's a small business (generally under 50 employees), they are often exempt from some labor laws and may not be legally required to pay you for vacation at all.
That said, you were considerate to give them 5 weeks notice; it is standard custom to give only 2 weeks. If you have been a valued employee and they have any ethics, they should in "good faith" either give you the time off or pay you for it. However, if they don't, there's really nothing you can do, short of suing them. I'd take the high road, let it go and be happy you are moving on to something better. Good luck.