Putting textures on big map

Hello I have big map for game and now I must to put textures. How to make this, because this map is from blender and I can’t use BSP-Surface properties settings. What method to use? I can’t find tutorial for this how to put textures for very largest objects.

you can assign may different materials with their unique UV in a 3d programm and each can have a different texture. import the model and the textures in UEd and youre fine.