Using a weatherproof electrics box for pet heating

I neee to fit a 50w heat bulb inside a rabbit-hutch to keep my pet tortoise warm overnight. I was planning on plugging the light fixture into a Weatherproof electrics box (such as Masterplug Water Resistant protection box available at DIY shops) which I would then plug into the mains inside my house by drilling through the brick work and feeding the wire through. I’d likely store the Weatherpoof box inside or underneath the hutch. Are there any safety precautions I’ve overlooked? The alternative would be to fit a longer wire onto the actual light fitting and feed this directly into the house through the brickwork but I feel this opens up more possibility for errors in DIY.