The 18-55 isn’t a very fast or sharp lens. In the night shots, you will need to crank up the sensitivity of the sensor to get enough “light” to the sensor. That will create more noise and lower the video’s overall quality.
That being said, it doesn’t sound like you will be up against the hardest panel of judges. If they won’t notice the noise, than there is no point in fighting it.
If you can get yourself the 50mm 1.8, it will be a lot faster. There is a shitty little focus ring on it, so manually focusing is tough, but for tripod shots with little action in the scene, it will help at night more. It’s $139.99 CDN.
For your purposes, the 18-55 will probably suffice. I’d personally feel better with more options.