At the risk of not providing a very good reply.
But... When I lived in New Zealand I worked a lot with a guy who did concreting as his job. I went to his house a few times, and he had done his with concrete.
What he did was use regular concrete base, then plaster (what he called it) which was light colour sand and cement mix, which a high ratio of cement, smoothed really well. Once dried he etched lines also into it. Honestly best patio I've ever seen.
It all depends on whether you can and are willing to loose the extra inches in height if you were to build up on the current patio?My patio is looking tired it's roughly 5m X 15m and is currently slabbed.
What are outside porcelain tiles like? Would I be able to tile over the existing patio or should bi just rip it up and relay?