I smiled as I read this (in Denise Mina’s The Last Breath), and wondered how many people would understand it. I am not sure if it is common in Scotland or if it is an older saying, but in Ireland, getting the messages is doing the shopping. A hot press is the warming cupboard.
I probably only know this because I am half-Irish, and lived and trained as a teacher in Ireland. I am not sure if only older people use it.

I didn’t know the phrase getting messages, but do know about a hot press!
That’s so cool!
I have to say I hadn’t heard about it. I really thought that the lady lived in a small village and she needed to go to the main post office to get her mail there.
Almost everyone in Scotland says getting messages is going shopping. I was brought up there so I understood it without your explanation. The hot press wasn’t an expression I had come across before for a warming cupboard, we called it an airing cupboard.
I love it? I wonder what the reason was? Was food or errands called messages?