Doing her hair and makeup would have been a rational decision also
Imo if sheila did the deed she would have wIted until she wS back in london, she didnt like whf, she would have killed herseld and her sons in her own home, also she would have wanted to die next to her children.
Now if she did it at whf, then the same thing would happened, she would have wanted to die next to her kids.
But the supposed conversation, around the kitchen table, of social services being brought in and to Sheila, the possibility of someone else having her children, of her losing them, could have sent her over the edge. The panic, the fear, the anxiety could be enough to bring upon a sudden lapse of rational thinking, depending on her then state of mind.
Maybe the phone calls where to be made the following day, to ask for help. Sheila may not have fully understood exactly what was being said and flipped....or panicked.
Something within Sheila's mind takes over, and she sets out to ensure she is never seperated from her sons. To ensure this, her sons would be first on the list. Next, mum and dad.
In this state, she then prepares herself for being re-united not only with her sons, but with her mu and dad. If she did do this, she also made sure the boys never missed their grandparents.......and if the phone call is to be believed also, she also tried to make sure her sons never went without their uncle Jeremy too.
Maybe her thinking was to keep the family together - they were not going to be seperated, she loved her sons so much, she did it for them.
Crazy, irrational.....but is this not something that could have been going through Sheila's mind, before she embarked upon her plan to solve the problem that she understood the family had and it's consequences?