There is a gap or drop at edge of garden which can be filled about a metre high and sloped off. In other words, it could be half or one side of a typical hugelkulture bed and will only be about 5 foot wide and 7 metres along the warmer south facing side of garden.
I know beds are meant to drop and flatten out, so is inside going to drift out and leave a sink, or might face of it just cave in and justabout turn out okay? Spose it depends in large part on how i do it.
*Decided to make a proper hugelkultur elsewhere after sleeping on it.