Thank you roj leather and Simon for your recommendations. I like the hanging chair and the almanda creeper on the wall. This will certainly liven up the patio.

immihunk, not sure what you mean by "strong enough to guarded". Are you looking to do a roof top garden? What is your objection to wood decking? It is strong, lightweight and will make a fine deck surface that allows drainage. We've don a few with removable panel systems for cleaning and maintenance. I'll monitor this discussion and maybe you can fill me in?

Eventually when you come to resell, a pool is an added plus. But for your own purposes, emptying the pool and adding a deck over it with a hinged door and steps placed below would be great for storage (as per option b but bearing in mind you could revert). All the best for your lovely new home.

Consider composite decking material which are more durable.