I would use a 9" angle grinder with a suitable diamond blade. Rather dusty though.
If you are not confident then hire a wet bridge saw.
https://www.hirestation.co.uk/tool-hire/Cutting/Tile-Cutter-Hire/210142/
I have never used the firm above. It was the first Google response. It will cost you about £100 for a weekend hire. As a DIYer, and especially as one that doesn't have a 9 inch angle grinder, it might be prudent to hire the bridge saw. They are very easy to use. Fill them up with water, drop the tile down and slowly push the cutter forward. BTW, they are also known as radial tile saws
Before hiring one though, double check any additional costs- eg, if it 110v- do they include the hire of the 110v transformer? How is the wear and tear on the diamond blade calculated? What are the delivery costs?
I have only ever laid porcelain inside houses. If your concrete base is level, I believe that you can use regular waterproof tile adhesive using a suitable notched tile rather than a dry mix base.
Given that you haven't had much joy here, you could try the following forum if you want more advice.
https://www.tilersforums.com/
I would highly recommend a "tile levelling system" if you want the patio to be flat. Typically, they are little "posts" that you put at the corner of each tile and then use cups or wedges to force the adjacent tiles down to the same plane.
https://www.sunrisetools.co.uk/tiling/
Again the above is just an example, I am not endorsing the company or product.
Best of luck. Please do let us know how you get on though. It helps others.