Roofing Job - Discovery, GP, 1709

We have an outside Lapa room, roofed with Harvey tiles outside, and a thatch grass roof look on the inside. The problem is that it started to leak through the grass at 2-3 places. Due to the roof being built like that one can't climb on top with full body weight to investigate. The leaks are minor but it causes damage the more we wait. I would really require a quote first to see how we can get it waterproofed due to the heavy rain.