Thinking laterally about this, it doesn’t have to be an EM gauge layout in the garden.
Given that the critical clearances around the turnout vee and point blades are (as I understand it – I’m an EMGS member to P4 standards) the same as OO standards, then it must be the case that there is a direct parallel. So any articles dealing with the benefits and challenges of OO in the garden will be relevant to EM in the garden, except for the distance between the rails.
I definitely remember a whole suite of OO garden railways in the Railway Modeller, back in the days when I used to take it every month. If there is an online index, like there is for MRJ, then you could find them easily.