Jim GM4DHJ wrote:

Over 600mm change in level you need a landing regardless of the door
opening in .....over 600mm you need a balustrade on the landing and a
handrail to the stair ....well that is how it was 10 years ago in Scotland
but things might be sillier these days ......

Thanks for that. The drop from my two doors is pretty much exactly 600mm
but I was imagining the first step to be below that rather than level with
it. The back door opens outwards, the patio door sideways (of course) which
might also affect things, I suppose.