Will it heat up the cage? The wooden vivarium's are on special. Hope it will work - Leopard Geckos don't need any lights, just a UTH pad. IF I should use an aquarium instead, tell me how to use the heat pad? I've heard of people where the glass cracked from a UTH so yeah :/
If you use a UTH in a wooden tank you will need to put it inside the tank - wood is not a very good conductor, it is on the other hand a very good insulator so (in theory) it would hold the heat in the tank better. If you use a glass tank you would stick the UTH on the outside of the tank. In either case it is best to hook up a thermostat/rheostat/dimmer to the heat pad to make sure that it doesn't get too hot for your reptile.