You may have to dig for the variety of outdoor tile you find in Spain but it is available. When practicing landscape design in California, I found beautiful landscape tiles out of Mexico. Rather than pouring concrete under tile, I would think about something more forgiving for a base like compacted gravel and sand.
Let me say up front that in my opinion stamping a large area of concrete is not a do it yourself project. You should consult with an artisan that may have the number of molds needed (you will need many for a patio), knows how to order the proper slump to the concrete, can color it to just what you want, and will be adept at mold releases and finishing the stamped pattern. It all has to happen quickly within a small time window for a patio. I would hate to see it get away from you and you end up having to chip out and toss a new patio attempt.
Another approach I would encourage you to explore if budget is an issue is simulating tile and grout with a nicely poured slab and concrete stains. Again, a concrete artisan is probably in your future although this could be a diy project I guess. These images show stained interior concrete floors but no reason they could not be outside although you would want some tooth to them so as not to create an ice rink surface. You might combine a stamped pattern you like with colorants and staining?
Have you scaled out your yard on paper? I think you will find it handy to have a scaled drawing for many reasons. And, if you are chipping out the old patio, be sure and think about adding any low voltage lighting, drip irrigation supply lines, or firepit gas lines you might want now or later under the new pour?
I loved Philly enough to almost take on a residence in Olde City once. Brotherly Love and all that. Got caught in a battle between the historical preservation folks and the City for no reason and was just not willing to bribe my way out of it. I do miss spending time in the place.