All this down to your own budget and usage.
1" roof sandwich panel should be sufficient.
Roof - Best to choose BlueScope brand for self assurance and warranty purposes, 0.35 minimum to 0.5 thickness.
Base panel - You can go BlueScope or cheaper brand and go 0.5 (thickness) the better as it would look very flat. I would recommend 3d wood pattern type.
Ask your supplier that PU foam is closed cell or open cell. Always go for closed cell if possible. Closed cell has better performance against sound and heat.
A tip for you to make sure the roof panel is longer than base panel by 5-10cm. To reduce rain entering the pu foam.
Cheers
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