The Tier 2 rules are also "work from home if you can" - this doesn't mean "bring the photoshoot to your home". I also think you've interpreted the law wrong - where does it say it's fine to invite up to 30 people into your private home if they're work colleagues?not white knighting her but you are allowed if it’s for work.
Up to 30 people can meet indoors for work purposes if the place they’re meeting is following covid guidelines
As others have pointed out, conducting a photoshoot in your private home, where other housemates live, is very different to conducting a photoshoot in a large, airy studio where you can guarantee social distancing. Considering Grace has posted videos of photoshoots in her home before and crews weren't wearing masks or social distancing I don't see why she should be given the benefit of the doubt here.