The standard size for a catering marquee is 6 meters x 3 meters.
If you are hiring in wedding caterers you will need to find out from them if they are using gas cookers (this is the usual way as they do not know if they will have access to electricity) or if your wedding venue has access to electricity.
Also, what power rated generator they require, combined with your own needs for perhaps the band or DJ and lights etc.
Another extra requirement your event caterers might require is wooden flooring or matting in the caterers tents. Party On Marquees hire out 'hard floor' which is about the cheapest way to provide a firm surface and flatter than matting.
Large frame tent catering option
Splitting your frame tent into different sections also reduced the total cost of hiring the tent. The splitting may increase the noise in the tent and also the cooking smells. This also gives your caterers ease of access, especially important if it is raining or windy.