John Rumm wrote:

Building regs approved document K has chapter and verse on steps:

Unless I'm missing it (which is entirely likely) I can't see anything there
which specifically relates to outside steps and landing size, but I found at
least one other site which specifies a minimum exterior landing depth of
36".

I had been thinking of a comparatively open, perhaps iron-work, set of steps
(with handrails) on pillars, but a three-foot landing will surely need
something rather more substantial and solid. How is something like that
built onto a property without compromising the damp-proof course? Does
there have to be a small but definite gap between it and the building's
wall? I'll investigate.