David Hill wrote:

Why not use paving slabs or half slabs on edge to make the beds, they
will never rot

True, but partly for appearance, and partly because anything involving
conceting things into place takes me forever and does my back in - taken
me long enough to set round topped kerbing round two edges of the
garden, perhaps overkill, but they'll never move and end-up looking all
straggly toothed like the bricks set on edge I inherited.

Armed with an impact driver and circular saw, I can knock up the beds
pretty quickly I reckon ...