Welcome James
One enquiry for every 100 visitors sounds very low, especially as it's a freephone number, so I'd suggest 3 things:-
(1) Improve the look of your site to make it more professional-looking. As it is, it gives the impression that it was designed by an amateur - there's a lot wrong with it. Sorry to be so blunt, but impressions do matter. It may be wise to hire a professional website designer to do it for you.
(2) Check the searchterms that people are clicking your AdWords for, because they may be searching on searchterms that show they are not really in the market for what you offer. Then refine your searchterms to refine the people who click on your ads.
(3) Check your AdWords text to make sure that it isn't attracting people who are not really interested in your products.