The Environment Agency (EA) is keen that waste wood should be recovered rather than consigned to landfill, but the use of waste wood as a fuel is subject to various restrictions.
First of all, it is important to be sure whether your wood is actually classified as waste. Wood such as branches and vegetation removed during gardening or grounds maintenance, and trees removed from watercourses following flooding, are classified as virgin timber rather than waste and can be freely used as fuel.