Yes, not an easy crime scene, if there is such a thing.
I have seen some gruesome crime scenes and this doesn't really compare I think that when you see a decapitated head they are the most sickening.
In any event, WHF seems to have had a hodgepodge of crap all over not a show kitchen by any measure. Even the plates are mismatched. My mother, grandmothers or wife would never mix and match different patterns like that. We have 48 (24 dinner size and 24 salad size) plates that match to make sure that when there are a large amount of guests that all get the same plate. It is blasphemy to even consider mixing. The exception being plain white bowls that are used for soup, cereal or side dishes. But that is why they have no pattern and are plain.
It looks like the table was set for breakfast the night before, my paternal grandmother used to do that. I never saw anyone leave out an empty butter dish though, I guess they lacked room in the fridge for it. We always keep the butter dishes in the fridge with butter already in them.
The sheer amount of stuff around shows it was a well used kitchen not one that was kept in perfect order. The buckets are against the wall so out of the way so they were not harming anyone and wouldn't impact food preparation which obviously would be done on the other side of the kitchen. There isn't really much food prep space so I would expect the table to be used but that seems not to be the case I guess the pantry was used for that.
Since the housekeeper knew that in the past Sheila had left her underwear soaking in the kitchen that means June didn't move it from the kitchen and that the housekeeper found it there and presumed that since it was Sheila's underwear and she knew June to leave soaking laundry in the scullery that it was Sheila who left it in the kitchen to soak.
The clothing was left there either Monday evening or sometime Tuesday because it wasn't there when the housekeeper left. That would be logical since it would either be Monday evening when the boy's would change out of dirty clothing or sometime Tuesday. Sometime Tuesday they went shopping and presumably that is when Sheila bought tampons.
None of this supports the suggestion that she was up very late and decided at that point to soak her panties and her son's dirty pants. If she planned to commit murder suicide then soaking the clothes would not make any sense because someone who decided to kill her sons or had just killed them would not need the boys' pants so would not care about the stain and thus would not bother to wash them nor would bother to wash her own panties if she planned to kill herself because likewise she would have no use for them anymore so would not care if they got permanently stained.
The only logical conclusion is the clothing was placed to soak by Sheila at a point in time when murder and suicide were not contemplated.