Taking polaroids at wedding receptions is nice.

There are some things that you should be aware of:

• There's no polaroid film available any more. You can get modern film from the impossible project, but it does not develop as quickly as the original polaroid film. Waiting a long time for a polaroid image kind of defeats the point of using that technology.
• Fuji offers film in different formats. The instax wide is quite tempting for a wedding reception, because often people come in groups (families, couples, friends...), which are easier to frame in a horizontal format (compared to square polaroid). Take a look at it and see if that would work for you. In my experience, people don't bother about the aspect ratio being different to the original polaroid.
• Sharing pictures is difficult. Taking interesting images will lead to questions like "can we all have a copy of that image?" But with instant film, there's only one image. If you want to give those photos to the people, the entire group will only have on original. If these photos go into a guest book at the reception, this is not a problem, but keep it in mind, because people want to have copies of those images.
• Consider shooting digital and using a small photo printer.

I don't know the place and I do not know how much light there will be

Make yourself familiar with the place. Consider this a studio. You should create as much light as you need. Make yourself familiar with the camera that you are using and take a few test shots.