Car roof load laws/highway code?

So me and some friends are planning a trip to the beach... End of exams, summer thing. A mate and i have some surfboards that we want to take and I have bought a soft FCS rack. Now this isn't the sort of thing that I get worried about but its my mums car, a hatchback skoda fabia. So I just need to know what the load rules are. Im pretty sure that it wont be overloaded with the weight but what are the laws and highway code on overhang? Thanks, cant find the answer easily. If you have a website that gives the information please post it :)